The United States military has developed a number of Helicopter Armament Subsystems since the early 1960s. These systems are used for offensive and defensive purposes and make use of a wide variety of weapon types including, but not limited to machine guns, grenade launchers, autocannon, and rockets. Various systems are still in use, though many have become obsolete. Introduction The helicopter has added much to the modern battlefield, fomenting new strategies and tactics to use and deny its capabilities. In the air, against land-based threats, and at sea, helicopters can be used to attack, defend, and transport to react swiftly to the fluid tactical conditions of modern combat. The United States Army was one of the first to experiment with helicopters, yet slow to fully explore the possibilities of armed helicopter gunships. An armed helicopter was proposed and rejected in the early 1940s. The Korean War experience prompted more experiments to explore the idea of air mobile tactics, and by 1962, armed helicopters, for attack and defense. That year saw the deployment of the UTTHCO (Utility Tactical Transport Helicopter Company) to help the South Vietnamese Army and to test new air mobile theory. Weapons used by UTTHCO were often crude and made from parts and weapons readily available in the field. By 1965, the United States had deployed a truly Air Mobile unit, the 17th Cavalry, which began to use more standardized armament. Throughout US involvement in Vietnam the US Army, US Marine Corps, and US Air Force would develop and use a number of armament systems designed for a variety of helicopters, and would pave the way for more dedicated attack helicopters. With the arrival of dedicated gunship helicopters such as the AH-1 Cobra (since 1967) and later the AH-64 Apache, armament subsystems for non-specific types would begin to drop off, with mostly defensive armament packages remaining. Such armament packages, giving decidedly heavy armament to small or primarily transport helicopters, have become popular among second and third world countries who lack the funds for dedicated attack helicopters. Most of those systems bear some resemblance to the plethora of US systems that follow in this entry. Designated systems This is a list of systems as designated by the US Army: Transport and utility helicopters UH-1 Iroquois XM3, XM3E1/M3, and TLSS The M3, sometimes referred to as "Aerial Rocket Artillery" (ARA), consisted of two 2.75" 24-Tube rocket launchers, one on either