1st Australian Task Force, a force in which all nine battalions of the Royal Australian Regiment would serve. One of the heaviest actions of the war occurred in August 1966, with the Battle of Long Tan, wherein D Company, 6th Battalion, Royal Australian Regiment (6RAR) successfully fended off an enemy force, estimated at 2,000 men, for four hours. In 1968, Australian forces defended against the Tet Offensive, a Viet Cong military operation, and repulsed them with few casualties. The contribution of personnel to the war was gradually wound down, starting in late-1970 and ending in 1972; the official declaration of the end of Australia's involvement in the war was made on 11 January 1973. Post–Vietnam War Following the Vietnam War, there was a significant hiatus of operational activity by the Australian Army. In late 1979, in the largest deployment of the decade, the Army committed 151 troops to the Commonwealth Monitoring Force, which monitored the transition of Rhodesia to universal suffrage. A decade later in 1989, Australia deployed 300 army engineer personnel as the Australian contribution to the United Nations Transition Assistance Group in Namibia. The mission helped transition the country to independence from South African control. Recent history (1990–present) Peacekeeping Following the invasion of Kuwait by Iraq in August 1990, a coalition of countries sponsored by the United Nations Security Council, of which Australia was a part, gave a deadline for Iraq to withdraw from Kuwait of the 15 January 1991. Iraq refused to retreat and thus full conflict and the Gulf War began two days later on 17 January 1991. In January 1993, the Australian Army deployed 26 personnel on an ongoing rotational basis to the Multinational Force and Observers (MFO), as part of a non-United Nations peacekeeping organisation that observes and enforces the peace treaty between Israel and Egypt. Australia's largest peacekeeping deployment began in 1999 with the International Force for East Timor, while other ongoing operations include peacekeeping in the Sinai (as part of MFO), and the United Nations Truce Supervision Organization (as part of Operation Paladin since 1956). Humanitarian relief after the 2004 Indian Ocean earthquake in Aceh Province, Indonesia, Operation Sumatra Assist, ended on 24 March 2005. Afghanistan and Iraq Following the 11 September 2001 terrorist attacks, Australia promised troops to any military operations that the US commenced in response to the attacks. Subsequently, the Australian Army committed combat troops to Afghanistan in Operation