M1 Abrams

M1 Abrams
Type - Main battle tank
Place of origin - United States
Service history
In service - 1980-present
Wars - Gulf War / War in Afghanistan / Iraq War / 2011 Egyptian Revolution / War in Iraq / Saudi Arabian-led intervention in Yemen
Production history
Designer - Chrysler Defense (now General Dynamics Land Systems)
Designed - 1972-1975
Manufacturer - Lima Army Tank Plant (since 1980) / Detroit Arsenal Tank Plant (1982-1996)
Unit cost - US$6.21 million (M1A2 / FY99) Estimated in 2016 as US$8.92 million (with inflation adjustment)
Produced - 1979-present
No. built - approx. 10,400
Specifications
Mass - M1: 60 short tons (54 t) / M1A1: 63 short tons (57 t) / M1A1 SA: 67.6 short tons (61.3 t) / M1A2 SEP v2: 71.2 short tons (64.6 t) / M1A2 SEP v3: 73.6 short tons (66.8 t)
Length - Gun forward: 32.04 ft (9.77 m)
Hull length: 26.02 ft (7.93 m)
Width - 12 ft (3.66 m)
Height - 8 ft (2.44 m)
Crew - 4 (commander, gunner, loader, driver)
Elevation - +20° / -10°
Traverse - 9 seconds/360 degrees
Armor - Composite armor
Main armament - M1: 105 mm L/52 M68A1 rifled gun (55 rounds) / M1A1: 120 mm L/44 M256A1 smoothbore gun (40 rounds) / M1A2: 120 mm L/44 M256A1 smoothbore gun (42 rounds)
Secondary armament - 1 × 0.50 caliber (12.7 mm) M2HB heavy machine gun with 900 rounds / 2 × 7.62 mm (.308 in) M240 machine guns with 10,400 rounds (1 pintle-mounted, 1 coaxial)
Engine - Honeywell AGT1500 multi-fuel turbine engine / 1,500 shp (1,120 kW)
Power/weight - From 26.9 hp/t (20.05 kW/t) to 23.8 hp/t (17.74 kW/t)
Transmission - Allison DDA X-1100-3B
Suspension - High-hardness-steel torsion bars with rotary shock absorbers
Ground clearance - M1, M1A1: 0.48 m (1.6 ft; 19 in) / M1A2: 0.43 m (1 ft 5 in)
Fuel capacity - 504.4 US gallons (1,909 L)
Operational range - M1A2, road: 265 mi (426 km) / Cross country: 93-124 mi (150-200 km)
Maximum speed - M1A1, road: 45 mph (72 km/h) (governed); Off-road: 30 mph (48 km/h) / M1A2, road: 42 mph (67 km/h) (governed); Off-road: 25 mph (40 km/h)

The M1 Abrams is a third-generation American main battle tank designed by Chrysler Defense (now General Dynamics Land Systems) and named for General Creighton Abrams. Conceived for modern armored ground warfare and now one of the heaviest tanks in service at nearly 68 short tons (almost 62 metric tons), it introduced several innovative features, including a multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system, separate ammunition storage in a blow-out compartment, and NBC protection for crew safety. Initial models of the M1 were armed with a licensed-produced 105 mm Royal Ordnance L7 gun, while later variants feature a licensed Rheinmetall 120 mm L/44.
The M1 Abrams was developed from the failure of the MBT-70 project to replace the obsolescent M60 tank. There are three main operational Abrams versions, the M1, M1A1, and M1A2, with each new iteration seeing improvements in armament, protection, and electronics. Extensive improvements have been implemented to the latest formerly designated M1A2 System Enhancement Package version 3 or SEPv3 and M1A2 SEPv4, respectively versions such as improved composite armor, better optics, digital systems and ammunition. The Abrams was due to be replaced by the Future Combat Systems XM1202 but due to its cancellation, the U.S. military has opted to continue maintaining and operating the M1 series for the foreseeable future by upgrading with improved optics, armor and firepower.
The M1 Abrams entered service in 1980 and currently serves as the main battle tank of the United States Army and formerly the Marine Corps. The export version is used by the armies of Egypt, Kuwait, Saudi Arabia, Australia, and Iraq. The Abrams was first used in combat in the Persian Gulf War and has seen combat in both the War in Afghanistan and Iraq War under U.S. service, while Iraqi Abrams tanks have seen action in the war against Islamic State and have seen use by Saudi Arabia during the Yemeni Civil War.
History

Previous developments
Through the 1960s the US Army and West German Army had collaborated on a single design that would replace both the M60 tank and the Leopard 1. The overall goal was to have a single new design with improved firepower to handle new Soviet tanks like the T-62, while providing improved protection against the T-62's new 115 mm smoothbore gun and especially high-explosive anti-tank (HEAT) rounds.
The resulting design, the MBT-70, incorporated new technologies across the board. A hydropneumatic suspension provided excellent cross-country ride quality and also allowed the entire tank to be raised or lowered by the driver, with the lowest position placing the top of the tank only 6 feet (1.8 m) off the ground. New 1,500 hp-class engines powered the designs which could both reach 43 miles per hour (69 km/h), two new guns were introduced, a US 152 mm design whose primary long-range weapon was the Shillelagh missile, while the Germans introduced a new 120 mm smoothbore design.
While the design was highly capable, its weight continued to grow, as did its budget. By 1969, the unit cost stood at five times the original estimates, causing the Department of Defense to suspend the program. Development of the tank continued on an austere basis until January 1970, when the DoD ended its tank partnership with Germany.
As a result of the problems with the MBT-70, the U.S. Army introduced the XM803, using some technologies from the MBT-70 but removing some of the more troublesome features. This succeeded only in producing an expensive system with capabilities similar to the M60. Congress canceled the XM803 in December 1971 but permitted the Army to reallocate $20 million remaining funds to develop a new main battle tank.
Starting afresh
The Tank-automotive and Armaments Command (TACOM) began examining specific goals. After several rounds of input, the decision was made to provide armor to defeat the "heavy threat" posed by the T-62's 115 mm gun using projected improvements of their armour-piercing fin-stabilized discarding sabot (APFSDS) ammunition through the 1980s, and the new 125 mm gun of the T-64 and T-72 firing high-explosive anti-tank (HEAT) rounds. To this end, a new design basis emerged in February 1973. It had to defeat any hit from a Soviet gun within 800 meters and 30 degrees to either side. The tank would be armed with the 105 mm M68 gun, a licensed version of the Royal Ordnance L7, and a 20 mm version of the M242 Bushmaster.
In May 1973, Chrysler Defense and General Motors submitted proposals. Both were armed with the 105 mm M68 gun, the licensed L7, and the 20 mm Bushmaster. Chrysler chose a 1,500 hp gas turbine Lycoming AGT1500. GM's model was powered by a 1,500 hp diesel similar to that used on the American MBT-70 and XM803.
Examining the experiences of the Yom Kippur War that year, a number of design changes were made. The newly created "Burlington" armor from the British Army's labs was incorporated to improve protection, especially against HEAT, and to incorporate the new armor package, the original goal of keeping weight under 50 short tons (45 t) was abandoned. The Bushmaster was seen as superfluous and was deleted. As TACOM continued to improve the detailed design, initial samples of the armor system were sent to the Ballistic Research Laboratory for testing.
At the time, the Pentagon's procurement system was beset with problems being caused by the desire to have the best possible design. This often resulted in programs being canceled due to cost overruns, leaving the forces with outdated systems, as was the case with the MBT-70. There was a strong movement within the Army to get a new design within budget to prevent the MBT-70 experience from repeating itself. For the new design, the Army stated the unit cost was to be no more than $507,000 in 1972 dollars (equivalent to $3,280,000 in 2021).
The Pentagon's approach to control of research and development was modified with the XM1. Previous acquisition strategy called for a significant amount of the design work be done by the government. Under the new framework, contractors would competitively bid their own designs rather than compete solely for the right to manufacture the end product.
More changes
Through the period while the initial prototypes were being built, a debate broke out between Germany and US about the use of the 105 mm gun. The Army was planning on introducing several new types of ammunition for the 105 that would greatly improve its performance, notably, the XM-774 using depleted uranium. These rounds would give it the performance needed to defeat any Soviet tank with ease. There was some concern that depleted uranium would not be allowed in Germany, perhaps just in peacetime, so improvements to the tungsten cored M735 were also considered.
Through this same period, there was an ongoing effort to improve NATO logistics by standardizing ammunition to the maximum possible degree. The Germans were moving ahead with their 120 mm gun on the Leopard 2K, and noted that the British had also introduced a 120 mm gun of their own in keeping with their long-range combat doctrine.
By 1977 the decision had been made to eventually move the new tank to a 120 mm gun. After head-to-head testing between the Royal Ordnance L11A5 and the Rheinmetall Rh-120, the latter was chosen. The turret designs of the two prototypes were modified to allow either gun to be fitted. Although the L11/M256 120 mm gun was chosen to be the main weapon of the M1 Abrams in 1979, the improved ammunition for the gun still was not fully developed, thus delaying its fielding until 1984.
The early production versions of the M1 Abrams (M1 & IPM1) were armed with the M68A1 for two reasons. First was due to the large number of M60 tanks with the M68E1 gun still in widespread US service in the 1980s and a large on-hand stockpile of 105 mm munitions. Fitting the M1 with the M68A1 gun was viewed as an economical and practical solution that allowed for commonality in ammunition among the two types of tanks. Secondly was that the M68A1 could employ the newly developed M900 APFSDS depleted uranium round that had improved penetration performance in comparison to the M774.
Prototypes
Prototypes were delivered in 1976 by Chrysler and GM armed with the license-built M68E1 version of the 105 mm Royal Ordnance L7. They entered head-to-head testing at Aberdeen Proving Ground, along with a Leopard 2 AV prototype for comparison. The Leopard 2 was found to meet U.S. requirements but was thought to cost more. The testing showed that the GM design was generally superior to Chrysler's, offering better armor protection, and better fire control and turret stabilization systems. These early preproduction prototypes were provisionally armed with the M68E1 105 mm main gun while a preferred 120 mm gun and its ammunition were in their design and component development phase. These prototypes used a combination mount that allowed for evaluating both 105 mm and 120 mm guns.
During testing, the power packs of both designs proved to have issues. The Chrysler gas turbine engine had extensive heat recovery systems in an attempt to improve its fuel efficiency to something similar to a traditional internal combustion engine. This proved not to be the case: the engine consumed much more fuel than expected, burning 3.8 gallons per mile. The GM design used a new variable-compression diesel design.
By spring 1976, the decision to choose the GM design was largely complete. In addition to offering better overall performance, there were concerns about Chrysler's engine both from a reliability and fuel consumption standpoint. The GM program was also slightly cheaper overall at $208 million compared to $221 million for Chrysler. In July 1976, Lt. Colonel George Mohrmann prepared a stack of letters informing Congress of the decision to move ahead with the GM design. All that was required was the final sign-off by the Secretary of Defense, Donald Rumsfeld.
Chrysler is chosen
On 20 July 1976, United States Secretary of the Army Martin Hoffman and a group of generals visited Deputy Defense Secretary Bill Clements and Director of Defense Research and Engineering Malcolm Currie on their decision. They were surprised when Clements and Currie criticized their decision and demanded the turbine be selected. Donald Rumsfeld heard arguments from both in the afternoon and asked for twenty-four hours to review the issues. The Army team spent the night writing briefs and presented them to Rumsfeld the next morning, who then announced a four-month delay.
Within days, GM was asked to present a new design with a turbine engine. According to Assistant Secretary for Research and Development Ed Miller, "It became increasingly clear that the only solution which would be acceptable to Clements and Currie was the turbine... It was a political decision that was reached, and for all intents and purposes that decision gave the award to Chrysler since they were the only contractor with a gas turbine.". However, the Chrysler design had the advantage that the entire power pack had room to be replaced by any number of engine designs, including a Diesel if needed.
The turbine engine does not appear to be the only reason for this decision. Chrysler was the only company that appeared to be seriously interested in tank development; the M60 had been lucrative for the company and relied on that program for much of its profit. In contrast, GM made only about 1% of its income from military sales, compared to 5% for Chrysler, and only submitted their bid after a "special plea" from the Pentagon.
On 12 November 1976, the Defense Department awarded a $20 billion development contract to Chrysler.
Production starts
In January 1978, a program was initiated to develop an enhanced version of the 105 mm gun, the M68A1 as a possible alternate weapon for the M1 Abrams. The new XM24/L55 gun barrel was 18 inches (45.72 cm) longer in comparison to the XM24/L52 barrel used on the M60 tanks. It has a higher chamber pressure, reinforced breech and a higher muzzle velocity.
Low rate initial production (LRIP) of the vehicle was approved on 7 May 1979. In February 1982, General Dynamics Land Systems Division (GDLS) purchased Chrysler Defense, after Chrysler built over 1,000 M1s. The M1 Abrams was the first vehicle to adopt Chobham armor.
A total of 3,273 M1 Abrams tanks were produced during 1979-1985 and first entered U.S. Army service in 1980. Production at the government-owned, GDLS-operated Lima Army Tank Plant in Lima, Ohio, was joined by vehicles built at the Detroit Arsenal Tank Plant in Warren, Michigan from 1982 to 1996. The U.S. Army Laboratory Command (LABCOM), under the supervision of the United States Army Research Laboratory (ARL), was also heavily involved with designing the tank with M1A1 armor resistant shells, M829A2 armor-penetrating rounds, and improved weapon range.
The M1 was armed with the license-built M68A1 version of the 105 mm Royal Ordnance L7 gun. The tank featured the first of its kind Chobham armor. The M1 Abrams was the first to use this advanced armor. It consisted of an arrangement of metal plates, ceramic blocks and open space. An improved model called the M1IP was produced briefly in 1984 and contained upgrades to armour and other small improvements. The M1IP models were used in the Canadian Army Trophy NATO tank gunnery competition in 1985 and 1987.
About 5,000 M1A1 Abrams tanks were produced from 1986 to 1992 and featured the M256 120 mm (4.7 in) smoothbore cannon developed by Rheinmetall AG of Germany for the Leopard 2, improved armor, consisting of depleted uranium and other classified materials, and a CBRN protection system. Production of M1 and M1A1 tanks totaled some 9,000 tanks at a cost of approximately $4.3 million per unit.
In 1990, Project On Government Oversight in a report criticized the M1's high costs and low fuel efficiency in comparison with other tanks of similar power and effectiveness such as the Leopard 2. The report was based on data from U.S. Army sources and the Congressional record. By 1999, costs for the tank were upwards of US$5 million a vehicle.
As the Abrams entered service, they operated alongside M60A3 within the U.S. military, and with other NATO tanks in various Cold War exercises which usually took place in Western Europe, especially West Germany. The exercises were aimed at countering Soviet forces.
Adaptations before the Persian Gulf War (Operations Desert Shield and Desert Storm) gave the vehicle better firepower and NBC (Nuclear, Biological and Chemical) protection.
Persian Gulf War
The Abrams remained untested in combat until the Persian Gulf War in 1991, during Operation Desert Storm. A total of 1,848 M1A1s were deployed to Saudi Arabia to participate in the liberation of Kuwait. The M1A1 was superior to Iraq's Soviet-era T-54/T-55 and T-62 tanks, as well as T-72 versions imported from the Soviet Union and Poland. Polish officials stated that these no license-produced T-72 (nicknamed Lion of Babylon) tanks were finished before destruction of the Iraqi Taji tank plant in 1991.
The T-72s, like most Soviet export designs, lacked night-vision systems and then-modern rangefinders, though they did have some night-fighting tanks with older active infrared systems or floodlights. Very few M1 tanks were hit by enemy fire and none were destroyed as a direct result of enemy fire, none of which resulted in any fatalities. Three Abrams were left behind the enemy lines after a swift attack on Talil airfield, south of Nasiriyah, on February 27. One of them was hit by enemy fire, the two other embedded in mud. The tanks were destroyed by U.S. forces in order to prevent any trophy-claim by the Iraqi Army. A total of 23 M1A1s were damaged or destroyed during the war. Of the nine Abrams tanks destroyed, seven were destroyed by friendly fire and two intentionally destroyed to prevent capture by the Iraqi Army. Some others took minor combat damage, with little effect on their operational readiness.
The M1A1 could kill other tanks at ranges in excess of 2,500 metres (8,200 ft). This range was crucial in combat against previous generation tanks of Soviet design in Desert Storm, as the effective range of the main gun in the Soviet/Iraqi tanks was less than 2,000 metres (6,600 ft). This meant Abrams tanks could hit Iraqi tanks before the enemy got in range - a decisive advantage in this kind of combat. In friendly fire incidents, the front armor and fore side turret armor survived direct armor-piercing fin-stabilized discarding sabot (APFSDS) hits from other M1A1s. This was not the case for the side armor of the hull and the rear armor of the turret, as both areas were penetrated on at least two occasions by unintentional strikes by depleted uranium ammunition during the Battle of Norfolk.
During operations Desert Shield and Desert Storm some M1IP and M1A1s were modified locally in theater (in the war zone) by modification work orders (MWO) with additional rolled homogeneous armor plating welded on the turret front. The M1 can be equipped with mine plow and mine roller attachments.
Lessons from the war improved the tank's weapons sights and fire control unit.
Upgrades
The M1A2 was a further improvement of the M1A1, with a commander's independent thermal viewer, weapon station, position navigation equipment, and a full set of controls and displays linked by a digital data bus. These upgrades also provided the M1A2 with an improved fire control system. The M1A2 System Enhancement Package (SEP) added digital maps, Force XXI Battle Command Brigade and Below (FBCB2) Linux communications system capabilities for commanders, and an improved cooling system to compensate for heat generated by the additional computer systems.
The M1A2 SEP also serves as the basis for the M104 Wolverine heavy assault bridge. The M1A2 SEPv2 (version 2) added Common Remotely Operated Weapon Station (CROWS or CROWS II) support, color displays, better interfaces, a new operating system, better front and side armor, and an upgraded transmission for better durability.
Further upgrades included depleted uranium armor for all variants, a system overhaul that returns all A1s to like-new condition (M1A1 AIM), a digital enhancement package for the A1 (M1A1D), and a commonality program to standardize parts between the U.S. Army and the Marine Corps (M1A1HC). Improvements to survivability, lethality, and protection have been sought since 2014.
Iraq War
Further combat was seen during 2003 when U.S. forces invaded Iraq and deposed Ba'athist Iraqi leader Saddam Hussein in the Iraq War's Operation Iraqi Freedom. During the invasion, at least nine Abrams tanks were put out of action by fire from rocket-propelled grenades.
One achievement of the M1A1s was the destruction of seven T-72s in a point-blank skirmish (less than 50 yards (46 m)) near Mahmoudiyah, about 18 miles (29 km) south of Baghdad, with no U.S. losses. This was in the face of inadequately trained Iraqi tank crews, most of whom had not fired live ammunition in the previous year due to the sanctions then in operation and made no hits at point-blank range. In addition to the Abrams's heavy armament, some crews were also issued M136 AT4 shoulder-fired anti-tank weapons under the assumption that they might have to engage heavy armor in tight urban areas where the main gun could not be brought to bear.
Following lessons learned in Desert Storm, the Abrams and many other U.S. combat vehicles used in the conflict were fitted with Combat Identification Panels to reduce friendly fire incidents. These were fitted on the sides and rear of the turret, with flat panels equipped with a four-cornered "box" image on either side of the turret front. Some Abrams tanks were also fitted with a secondary storage bin on the back of the existing bustle rack on the rear of the turret (referred to as a bustle rack extension) to enable the crew to carry more supplies and personal belongings.
Several Abrams tanks that were irrecoverable due to loss of mobility or other circumstances were destroyed by friendly forces, usually by other Abrams tanks, to prevent their capture. Some Abrams tanks were disabled by Iraqi infantrymen in ambushes during the invasion. Some troops employed short-range anti-tank rockets and fired at the tracks, rear and top. Other tanks were put out of action by engine fires when flammable fuel stored externally in turret racks was hit by small arms fire and spilled into the engine compartment. By March 2005, approximately 80 Abrams tanks were forced out of action by enemy attacks; 63 were restored, while 17 were damaged beyond repair with 3 of them at the beginning of 2003.
Vulnerabilities exposed during urban combat in the Iraq War were addressed with the Tank Urban Survival Kit (TUSK) modifications, including armor upgrades and a gun shield, issued to some M1 Abrams tanks. It added protection in the rear and side of the tank and improved fighting ability and survival ability in urban environments. By December 2006 more than 530 Abrams tanks had been shipped back to the U.S. for repairs and upgrades.
In May 2008, it was reported that a U.S. M1 tank had also been damaged in Iraq by insurgent fire of a Soviet-made RPG-29 "Vampir", which uses a tandem-charge high-explosive anti-tank warhead to penetrate explosive reactive armor (ERA) as well as composite armor behind it. The U.S. considered the RPG-29 a high threat to armor and refused to allow the newly formed Iraqi Army to buy it, fearing that it would fall into the insurgents' hands.
Iraqi Army service
Between 2010 and 2012 the U.S. supplied 140 refurbished M1A1 Abrams tanks to Iraq. In mid-2014, they saw action when the Islamic State of Iraq and the Levant launched the June 2014 Northern Iraq offensive. During three months, about one-third of the Iraqi Army's M1 tanks had been damaged or destroyed by ISIL and some were captured by opposing forces. By December 2014, the Iraqi Army only had about 40 operational Abrams left. That month, the U.S. Department of State approved the sale of another 175 Abrams to Iraq.
Iranian-backed Iraqi Shiite Kata'ib Hezbollah (Hezbollah Brigades) were reported to operate M1 Abrams, and released publicity showing the tanks being transported by trucks to take part in the Battle of Mosul. It is not known whether the tanks were captured from ISIS, seized from Iraq's military, or handed over.
One Iraqi-operated Abrams has been nicknamed "The Beast" after it became the lone working tank when taking back the town of Hit in April 2016, destroying enemy fighting positions and IED emplacements.
In October 2017, Abrams were used by the Iraqi security forces and the Popular Mobilization Forces (also called Al-Hashd al-Shaabi) in assaults against the Kurdistan Regional Government Peshmerga in the town of Altun Kupri (also called Prde). It was claimed by Kurdish commanders that at least one Abrams was destroyed by the Peshmerga.
War in Afghanistan
Tanks may have limited utility in Afghanistan due to the mountainous terrain, although Canada and Denmark deployed Leopard 1 and 2 MBTs that were specially modified to operate in the relatively flat and arid conditions of southwestern Afghanistan. In late 2010, at the request of Regional Command Southwest, the U.S. Marine Corps deployed a small detachment of 14 M1A1 Abrams tanks from Delta Company, 1st Tank Battalion, 1st Marine Division (Forward), to southern Afghanistan in support of operations in Helmand and Kandahar provinces.
2015 Yemen Civil War
After the start of the Saudi Arabian intervention in Yemen during the 2015 Yemeni Civil War, Saudi Arabian M1A2 MBTs were deployed near the Saudi Arabian/Yemeni border. In August 2016, the U.S. approved a deal to sell up to 153 more Abrams tanks to Saudi Arabia, including 20 "battle damage replacements", suggesting that some Saudi Arabian Abrams had been destroyed or severely damaged in combat in Yemen.
Production shutdown
The U.S. Army planned to end production at the Lima Army Tank Plant from 2013 to 2016 in an effort to save over $1 billion; it would be restarted in 2017 to upgrade existing tanks. General Dynamics Land Systems (GDLS), which operates the factory, opposed the move, arguing that suspension of operations would increase long-term costs and reduce flexibility. Specifically, GDLS estimated that closing the plant would cost $380 million and restarting production would cost $1.3 billion.
By August 2013, Congress had allocated $181 million for buying parts and upgrading Abrams systems to mitigate industrial base risks and sustain development and production capability. Congress and General Dynamics were criticized for redirecting money to keep production lines open and accused of "forcing the Army to buy tanks it didn't need." General Dynamics asserted that a four-year shutdown would cost $1.1-1.6 billion to reopen the line, depending on the length of the shutdown, whether machinery would be kept operating, and whether the plant's components would be completely removed.
They contended that the move was to upgrade Army National Guard units to expand a "pure fleet" and maintain production of identified "irreplaceable" subcomponents. A prolonged shutdown could cause their makers to lose their ability to produce them and foreign tank sales were not guaranteed to keep production lines open. There is still risk of production gaps even with production extended through 2015. With funds awarded before recapitalization is needed, budgetary pressures may push planned new upgrades for the Abrams from 2017 to 2019.
In December 2014, Congress again allocated $120 million, against the wishes of the Army, for Abrams upgrades including improving gas mileage by integrating an auxiliary power unit (APU) to decrease idle time fuel consumption and upgrading the tank's sights and sensors.
In late 2016, tank production/refurbishment had fallen to a rate of one per month with less than 100 workers on site. In 2017, the Trump administration made rebuilding the military a priority. It was reported in 2018 that the Army had ordered 135 tanks re-built to new standards with employment at over 500 workers and expected to rise to 1,000.
Future plans
During the 1980s and 1990s, the Block III main battle tank from the Armored Systems Modernization (ASM) program was expected to succeed the M1 Abrams family in the 1990s. The design had an unmanned turret with a 140 mm main gun, as well as improved protection. The end of Cold War hostilities caused the end of the program. The tracked M8 Armored Gun System was conceived as a possible supplement for the Abrams in U.S. service for low-intensity conflict in the early 1990s. Prototypes were made but the program was canceled. The eight-wheeled M1128 Mobile Gun System was designed to supplement the Abrams in U.S. service for low-intensity conflicts. It has been introduced into service and serves with Stryker brigades.
The U.S. Army's Future Combat Systems XM1202 Mounted Combat System was to replace the Abrams in U.S. service and was in development when funding for the program was cut from the DoD's budget.
Engineering Change Proposal 1 is a two-part upgrade process. ECP1A adds space, weight, and power improvements and active protection against improvised explosive devices. Nine ECP1A prototypes have been produced as of October 2014. ECP1B, which will begin development in 2015, may include sensor upgrades and the convergence of several tank round capabilities into a multi-purpose round.
The Army anticipates that the remaining M1A1 fleet will remain in U.S. service until at least 2021, and the M1A2 to beyond 2050. The United States Army National Guard will continue using M1A1s for a lengthier, undetermined period; it took until 1997 for the M60A3 to be retired by the last National Guard units, as opposed to the active-duty U.S. Army, which had fully transitioned to the M1 by the end of 1990.
As of 2020, the Marine Corps has been pursuing a force restructuring plan named Force 2030. Under this directive all US Marine tank battalions were deactivated and its M1A1 tanks transferred to the Army by the end of 2021. In the future, any need the Marine Corps encounters for heavy armor will be met by the U.S. Army.
Design

Countermeasures

Camouflage
Earlier U.S. military vehicles, used from World War I through the Vietnam War, used a scheme of "olive drab", often with large white stars. Prototypes, early production M1 (105 mm gun) and M1-IP models switched to a flat forest green paint scheme. The large white insignia stars have also transitioned to much smaller black markings. Some units painted their M1s with the older Mobility Equipment Research and Design Command (MERDC) 4-color paint scheme but the turn-in requirements for these tanks required repainting them to overall forest green. Therefore, even though a large number of the base model M1s were camouflaged in the field, few or none exist today.
M1A1s came from the factory with the NATO three color camouflage Black/Med-Green/Dark-Brown Chemical Agent Resistant Coating (CARC) paint jobs. Today, M1A1s are given the NATO three color paint job during rebuilds. M1s and M1A1s deployed to Operation Desert Storm were hastily painted desert tan. Some, but not all, of these tanks were re-painted to their "authorized" paint scheme. M1A2s built for Middle Eastern countries were painted in desert tan. Replacement parts (roadwheels, armor skirt panels, drive sprockets, etc.) are painted olive green, which can sometimes lead to vehicles with a patchwork of green and desert tan parts.
Australian M1A1s were desert tan when delivered but have undergone a transition to the Australian Army vehicle standard 'Disruptive Pattern Camouflage'; a scheme that consists of black, olive drab, and brown.
The U.S. Army can equip its Abrams tanks with the Saab Barracuda camouflage system, which provides concealment against visual, infrared, thermal infrared, and broad-band radar detection.
Concealment
The turret is fitted with two six-barreled M250 smoke grenade launchers (USMC M1A1s used an eight-barreled version), with one on each side. When deployed, the grenades airburst, creating a thick smoke that blocks both visual and thermal imaging. The engine is also equipped with a smoke generator that is triggered by the driver. When activated, fuel is sprayed into the hot turbine exhaust, creating the thick smoke. Due to a risk of fires however, this system is sometimes disabled.
Armor
In July 1973, representatives from Chrysler and General Motors traveled to the United Kingdom, and were escorted by personnel from the Ballistic Research Laboratory and XM1 Project Manager Major General Robert J. Baer to witness the progress of British developed Chobham armor. They observed the manufacturing processes required for the production of Chobham armor, which was an arrangement of metal plates, ceramic blocks and open space; and saw a proposed design for a new British vehicle utilizing it.
HEAT and sabot rounds enter the beginning layers of armor but are unable to penetrate the crew compartment. Ceramics have the ability to absorb a great deal of heat, and can blunt physical blows by cracking and deflecting the force. The remaining hot gasses and metal shrapnel spread out or settle in empty air pockets. Both contractors reevaluated their proposed armor configurations based upon the newly obtained data.
This led to major changes in the General Motors XM1, the most prominent of which is the turret front changing from vertical to sloped armor. The Chrysler XM1 on the other hand retained its basic shape although a number of changes were made. The Ballistic Research Laboratory had to develop new armor combinations in order to accommodate the changes made by the contractors.
Similar to most other main battle tanks, the M1 Abrams feature composite armor only on the frontal aspect of the hull. However, the Abrams' turret features composite armoring across both the front and the sides. In addition, the side skirts of the frontal half of the hull are also made of composite, providing superior ballistic protection against chemical energy munitions such as HEAT rounds. The composition of the Abrams' composite armor consists of sandwiched plates of non-explosive reactive armor (NERA) between conventional steel plates. The NERA plates feature elasticity, allowing them to flex and distort upon perforation, disrupting the penetrating jets of shaped charges and providing more material and space for a kinetic round to pass through, thus providing increased protection compared to conventional steel armor of similar weight.
For the base model M1 Abrams, Steven J. Zaloga gives a frontal armor estimate of 350 mm vs armor-piercing fin-stabilized discarding sabot (APFSDS) and 700 mm vs high-explosive anti-tank (HEAT) warhead in M1 Abrams Main Battle Tank 1982-1992 (1993). In M1 Abrams vs T-72 Ural (2009), he uses Soviet estimates of 470 mm vs APFSDS and 650 mm vs HEAT for the base model Abrams. He also gives the Soviet estimates for the M1A1, 600 mm vs APFSDS, and 700 mm vs HEAT.
Armor protection was improved by implementing a new special armor incorporating depleted uranium and other undisclosed materials and layouts. This was introduced into the M1A1 production starting October 1988. This new armor increased effective armor particularly against kinetic energy rounds but at the expense of adding considerable weight to the tank, as depleted uranium is 1.7 times denser than lead.
The first M1A1 tanks to receive this upgrade were tanks stationed in Germany. US-based tank battalions participating in Operation Desert Storm received an emergency program to upgrade their tanks with depleted uranium armor immediately before the onset of the campaign. M1A2 tanks uniformly incorporate depleted uranium armor, and all M1A1 tanks in active service have been upgraded to this standard as well. This variant was designated as the M1A1HA (HA for Heavy Armor).
The M1A1 AIM, M1A2 SEP and all subsequent Abrams models feature depleted uranium in both the hull and turret armor. Each Abrams variant after the M1A1 have been equipped with depleted uranium armor of different generations. The M1A1HA uses first generation armor, while the M1A2 and M1A1HC use second generation depleted uranium. The M1A2 SEP variants have been equipped with third generation depleted uranium armor combined with a graphite coating. The M1A2C also features increased physical line-of-sight turret armor.
For the M1A1HA, Zaloga gives a frontal armor estimate of 600 mm vs APFSDS and 1300 mm vs HEAT in M1 Abrams Main Battle Tank 1982-1992, nearly double the original protection of the Abrams. In M1 Abrams vs T-72 Ural, he uses different estimates of 600 mm vs APFSDS and 700 mm vs HEAT for the front hull and 800 mm vs APFSDS and 1300 mm vs HEAT for the front of the turret. The protection of M1A2 SEP is a frontal turret armor estimate of 940-960 mm vs APFSDS and 1,320-1,620 vs HEAT, glacis estimate of 560-590 mm vs APFSDS and 510-1,050 vs HEAT, and lower front hull estimate of 580-650 mm vs APFSDS and 800-970 vs HEAT. The M1A2 SEPV3 increased the LOS thickness of the turret and hull front armor; total armor protection from this increase is not known.
In 1998, a program was begun to incorporate improved turret side armor into the M1A2. This was intended to offer better protection against rocket-propelled grenades more modern than the baseline RPG-7. These kits were installed on about 325 older M1A2 tanks in 2001-2009 and it was also included in upgraded tanks.
The Abrams may also be fitted with explosive reactive armor over the track skirts if needed (such as the Tank Urban Survival Kit) and slat armor over the rear of the tank and rear fuel cells to protect against ATGMs. Protection against spalling is provided by a kevlar liner.
Damage control
The tank has a halon firefighting system to automatically extinguish fires in the crew compartment. The engine compartment has a firefighting system that is engaged by pulling a T-handle located on the left side of the hull. The Halon gas can be dangerous to the crew. However, the toxicity of Halon 1301 gas at 7% concentration is much lower than the combustion products produced by fire in the crew compartment, and CO2 dump would be lethal to the crew.
The crew compartment also contains small hand-held fire extinguishers. Fuel and ammunition are stored in armored compartments with blowout panels intended to protect the crew from the risk of the tank's own ammunition cooking off (exploding) if the tank is damaged. The main gun's ammunition is stored in the rear section of the turret, with blast doors that open under power by sliding sideways only to remove a round for firing, then automatically close. Doctrine mandates that the ammunition door must be closed before arming the main gun.
Tank Urban Survival Kit
The Tank Urban Survival Kit (TUSK) is a series of improvements to the M1 Abrams intended to improve fighting ability in urban environments. Historically, urban and other close battlefields have been poor places for tanks to fight. A tank's front armor is much stronger than that on the sides, top, or rear. In an urban environment, attacks can come from any direction, and attackers can get close enough to reliably hit weak points in the tank's armor or gain sufficient elevation to hit the top armor.
Armor upgrades include reactive armor on the sides of the tank and slat armor (similar to that on the Stryker) on the rear to protect against rocket-propelled grenades and other shaped charge warheads. A Transparent Armor Gun Shield and a thermal sight system are added to the loader's top-mounted M240B 7.62 mm machine gun, and a Kongsberg Gruppen Remote Weapon Turret carrying a 12.7 mm (.50 in) caliber machine gun (again similar to that used on the Stryker) is in place of the tank commander's original 12.7 mm (.50 in) caliber machine gun mount, wherein the commander had to expose himself to fire the weapon manually. An exterior telephone allows supporting infantry to communicate with the tank commander.
The TUSK system is a field-installable kit that allows tanks to be upgraded without needing to be recalled to a maintenance depot. While the reactive armor may not be needed in most situations, like those present in maneuver warfare, items like the rear slat armor, loader's gun shield, infantry phone (which saw use on Marine Corps M1A1s as early as 2003), and Kongsberg Remote Weapons Station for the 12.7 mm (.50 in) caliber machine gun will be added to the entire M1A2 fleet over time.
In August 2006, General Dynamics Land Systems received a U.S. Army order for 505 Tank Urban Survivability Kits (TUSK) for Abrams main battle tanks supporting operations in Iraq, under a US$45 million contract. Deliveries were expected to be completed by April 2009. Under a separate order, the U.S. Army awarded General Dynamics Armament and Technical Products (GDATP) US$30 million to produce reactive armor kits to equip M1A2s. The reactive tiles for the M1 will be locally produced at GDATP's Burlington Technology Center.
Tiles will be produced at the company's reactive armor facility in Stone County Operations, McHenry, Mississippi. In December 2006, the U.S. Army added Counter Improvised Explosive Device enhancements to the M1A1 and M1A2 TUSK, awarding GDLS $11.3 million contract, part of the $59 million package mentioned above. In December, GDLS also received an order, amounting to around 40% of a US$48 million order, for loader's thermal weapon sights being part of the TUSK system improvements for the M1A1 and M1A2 Abrams Tanks.
Active protection system
In addition to the armor, some USMC Abrams tanks are equipped with a Softkill Active protection system, the AN/VLQ-6 Missile Countermeasure Device (MCD) that can impede the function of guidance systems of some semi-active control line-of-sight (SACLOS) wire- and radio guided anti-tank missiles (such as the Russian 9K114 Shturm) and infrared homing missiles. The MCD works by emitting a massive, condensed infrared signal to confuse the infrared homing seeker of an anti-tank guided missile (ATGM).
However, the drawback to the system is that the ATGM is not destroyed, it is merely directed away from its intended target, leaving the missile to detonate elsewhere. This device is mounted on the turret roof in front of the loader's hatch, and can lead some people to mistake Abrams tanks fitted with these devices for the M1A2 version, since the Commander's Independent Thermal Viewer on the latter is mounted in the same place, though the MCD is box-shaped and fixed in place as opposed to cylindrical and rotating like the CITV.
In 2016, the U.S. Army and Marine Corps began testing out the Israeli Trophy active protection system to protect their Abrams tanks from modern RPG and ATGM threats by either jamming (with ATGMs) or firing small rounds to deflect incoming projectiles. The Army planned to field a brigade of over 80 tanks equipped with Trophy to Europe in 2020. It is planned for up to 261 Abrams to be upgraded with the system, enough for four brigades. In June 2018, the Army awarded Leonardo DRS, U.S. partner to Trophy's designer Rafael, a $193 million contract to deliver the system in support of M1 Abrams "immediate operational requirements". U.S. Army M1A2 SEP V2 Abrams tanks deployed to Germany in July 2020 fitted with Trophy systems. Deliveries to equip four tank brigades were completed in January 2021.