The MIM-104 Patriot is a mobile interceptor missile surface-to-air missile (SAM) system, the primary such system used by the United States Army and several allied states. It is manufactured by the U.S. defense contractor Raytheon and derives its name from the radar component of the weapon system. The AN/MPQ-53 at the heart of the system is known as the "Phased Array Tracking Radar to Intercept on Target",[6] which is a backronym for "Patriot". In 1984, the Patriot system began to replace the Nike Hercules system as the U.S. Army's primary high to medium air defense (HIMAD) system and the MIM-23 Hawk system as the U.S. Army's medium tactical air defense system.[7] In addition to defending against aircraft, Patriot is the U.S. Army's primary terminal-phase anti-ballistic missile (ABM) system. As of 2016, the system is expected to stay fielded until at least 2040.[8] Patriot uses an advanced aerial interceptor missile and high-performance radar systems. Patriot was developed at Redstone Arsenal in Huntsville, Alabama, which had previously developed the Safeguard ABM system and its component Spartan and hypersonic Sprint missiles. The symbol for Patriot is a drawing of a Revolutionary War–era minuteman. The MIM-104 Patriot has been widely exported. Patriot was one of the first tactical systems in the U.S. Department of Defense (DoD) to employ lethal autonomy in combat.[9] The system was successfully used against Iraqi missiles in the 2003 Iraq War, and has also been used by Saudi and Emirati forces in the Yemen conflict against Houthi missile attacks. The Patriot system achieved its first undisputed shootdowns of enemy aircraft in the service of the Israeli Air Defense Command. Israeli MIM-104D batteries shot down two Hamas UAVs during Operation Protective Edge in August 2014, and in September 2014, an Israeli Patriot battery shot down a Syrian Air Force Sukhoi Su-24 which had penetrated the airspace of the Golan Heights, achieving the system's first known shootdown of a crewed enemy aircraft.[10]