The major treaty that ended the Persian Gulf War in 1991 was the United Nations Security Council Resolution 687. This treaty established a ceasefire between Iraq and coalition forces led by the United States, outlining the terms for ending hostilities after Iraq's invasion of Kuwait. It required Iraq to disarm and accept inspections, reshaping geopolitical dynamics in the region. This resolution established a framework for post-war relations and set the stage for subsequent conflicts involving Iraq, influencing Middle Eastern politics for years to come.