The M1 Abrams was developed during the Cold War as a successor to the canceled MBT-70. The M1 Abrams contract went to Chrysler Defense and was the first vehicle to adopt Chobham armor. Adaptations before the Persian Gulf War (Operations Desert Shield and Desert Storm) gave the vehicle better firepower and NBC (Nuclear, Biological and Chemical) protection. Being vastly superior to Iraqi tanks, very few M1 tanks were hit by enemy fire. Upgrades after the war improved the tank’s weapons sights and fire control unit. The invasion of Iraq in 2003 destroyed Iraq’s military. Vulnerabilities in urban combat were addressed with the TUSK modification. Three main versions of the M1 Abrams have been deployed, the M1, M1A1, and M1A2, incorporating improved armament, protection, and electronics. These improvements and other upgrades to in-service tanks have allowed this long-serving vehicle to remain in front-line service. In addition, development for the improved M1A3 version has been known since 2009. The M1A2 System Enhancement Package (SEP) is a successor to the M1A2. It is also an upgrade package for the older Abrams tanks. It has improved armor protection, improved system components, improved computer components, and some other improvements. First upgraded tank was delivered in 1999. A total of 240 M1A2 SEP tanks were newly built. Another 300 M1A2 tanks were upgraded to M1A2 SEP standard. Furthermore 400 oldest M1A1 tanks were upgraded to M1A2 SEP. Also unknown number of the basic refurbished M1 tanks were upgraded to this standard. So the US military operates at least 900 main battle tanks upgraded to this standard. It is the backbone of the US military armored forces. This tank has not been exported. It is planned that the fleet of refurbished and upgraded M1A1 tanks will remain with the US military service until at least 2021. The M1A2 tanks will remain in service beyond 2050. The M1A2 SEP is one of the best main battle tanks in the world. It has incredible technology and armor. Upgraded tanks are slightly heavier than the baseline M1A2. The baseline M1A2 tank uses advanced armor, reinforced with depleted uranium layers. The M1A2 SEP has a further upgraded depleted uranium armor components with graphite coating. Protection of this MBT is considered as one of the best in the world. The M1A2 SEP has significant level of protection against all known anti-tank weapons. It can also employ counter-IED equipment. Protection can be further increased with add-on explosive reactive armor. The tank is armed with the same 120-mm M256 smoothbore gun as its predecessor. Range of effective fire is in excess of 4 km. It can fire the M829A3 APFSDS rounds with depleted uranium penetrator and M1028 canister rounds that discharges massive blast of tungsten fragments at muzzle exit. This round has devastating lethality against assaulting infantry between a range of 200-500 meters. Ammunition for the main gun is stored in the turret bustle, fitted with blow-out panels. The SEPv2 (version 2) added CROWS or CROWS 2 remotely operated weapon station, armed with a 12.7-mm machine gun. This weapon can be fired from inside of the tank without exposing the crew to enemy fire. Also there are two 7.62-mm machine guns. One of them is mounted coaxially with the main gun. The other is mounted on top of the roof and is operated by the gunner. The SEPv3 (version 3) was publicly revealed in 2015. Today it is the most modern version of the Abrams tank. It has a number of upgrades in the area of survivability, maintainability, fuel efficiency, and network capabilities. Main survivability upgrades are the new armor package and improved anti-IED capability. Testing of this upgraded tank is planned to be completed in 2016. The SEPv3 should be delivered to the US Army starting in 2017. The M1A2 SEP has a more advanced fire control system with upgraded ballistic computer. Both the gunner’s sight and commander’s independent thermal viewer use new 2nd generation FLIR technology and have improved thermal imaging and night vision capabilities. Commander and gunner can designate and track multiple targets simultaneously. This gives the tank a hunter-killer engagement capability. This tank is fitted with a digital battlefield management system. It allows commanders to track friendly and hostile forces on the battlefield. This system is near real-time based. Locations of friendly vehicles are constantly updated. This system increases vehicle commander’s situational awareness. This tank is operated by a crew of four, including commander, gunner, loader and driver.