Operation Barrel Roll was a covert USAF 2nd Air Division (later Seventh Air Force) and U.S. Navy Task Force 77, interdiction and close air support campaign conducted in Laos between 14 December 1964 and 29 March 1973 concurrent with the Vietnam War. The initial purpose of the operation was to serve as a signal to North Vietnam to cease its support for the Viet Cong insurgency in South Vietnam. The operation became increasingly involved in providing close air support to the Royal Lao Armed Forces, CIA-backed Hmong forces, and Thai Army elements in a covert ground war in northern and northeastern Laos. The US pulled out of Laos in early 1973 as part of the Paris Peace Accords and the Case–Church Amendment of June 1973 prevented any further US military activity in Laos, Cambodia and Vietnam without Congressional approval.