In the late 1960s the United States Air Force requested a dedicated close air support (CAS) plane that became the Fairchild Republic A-10 Thunderbolt II. The A-10 was originally conceived as an anti-armor weapon (the A-X program requirements specifically called for an aircraft mounting a large rotary cannon to destroy massed Warsaw Pact armored forces) with limited secondary capability in the interdiction and tactical bombing roles. Today it remains the only dedicated fixed-wing ground-attack aircraft in any U.S. military service. Overall U.S. experience in the Gulf War, Kosovo War, Afghanistan and Iraq War has resulted in renewed interest in such aircraft. The U.S. Air Force is currently researching a replacement for the A-10 and started the OA-X program to procure a light attack aircraft.