History of the Panama Canal
During World War II, the canal proved a vital part of the U.S. military strategy, allowing ships to transfer easily between the Atlantic and Pacific. Politically, the Canal remained a territory of the United States until 1977, when the Torrijos–Carter Treaties began the process of transferring territorial control of the Panama Canal Zone to Panama, a process completed on 31 December 1999.
United States invasion of Panama
The United States invasion of Panama, codenamed Operation Just Cause occurred between mid-December 1989 and late January 1990. It occurred during the administration of President George H. W. Bush and ten years after the Torrijos–Carter Treaties were ratified to transfer control of the Panama Canal from the U.S. to Panama by 1 January 2000.