The United States invasion of Panama, codenamed Operation Just Cause, began in mid-December 1989 during the presidency of George H. W. Bush. The primary purpose of the invasion was to depose the de facto ruler of Panama, General Manuel Noriega, who was wanted by U.S. authorities for racketeering and drug trafficking. The operation concluded in late January 1990 with the surrender of Noriega. The Panama Defense Forces (PDF) were dissolved, and President-elect Guillermo Endara was sworn into office.

Noriega, who had longstanding ties to United States intelligence agencies, consolidated power to become Panama's de facto dictator in the early 1980s. In the mid-1980s, relations between Noriega and the U.S. began to deteriorate due to fallout of the murder of Hugo Spadafora and the removal of Nicolas Ardito Barletta. His criminal activities and association with other spy agencies came to light, and in 1988 he was indicted by federal grand juries on several drug-related charges. Negotiations seeking his resignation, which began under the presidency of Ronald Reagan, were ultimately unsuccessful. In 1989, Noriega annulled the results of the Panamanian general elections, which appeared to have been won by opposition candidate Guillermo Endara; President Bush responded by reinforcing the U.S. garrison in the Canal Zone. After a U.S. Marine officer was shot dead at a PDF roadblock, Bush authorized the execution of the Panama invasion plan.

On December 20, the U.S. invasion of Panama began. Panamanian forces were rapidly overwhelmed, although operations continued for several weeks. Endara was sworn in as president shortly after the start of the invasion. Noriega eluded capture for several days before seeking refuge in the Holy See diplomatic mission in Panama City. He surrendered on January 3, 1990 and was then flown to the U.S., where he was tried, convicted and sentenced to 40 years in prison.

The Pentagon estimated that 516 Panamanians were killed during the invasion, including 314 soldiers and 202 civilians. 23 U.S. soldiers and 3 U.S. civilians were killed. The United Nations General Assembly and the Organization of American States both condemned the invasion as a violation of international law.