The Gulf War was an armed conflict between Iraq and a 42-country coalition led by the United States. The coalition's efforts against Iraq were carried out in two key phases: Operation Desert Shield, which marked the military buildup from August 1990 to January 1991; and Operation Desert Storm, which began with the aerial bombing campaign against Iraq on 17 January 1991 and came to a close with the American-led liberation of Kuwait on 28 February 1991.