Why did democracy return to Panama in 1990?

Democracy returned to Panama in 1990 primarily as a result of the United States invasion of Panama, known as Operation Just Cause, which ousted the military dictator Manuel Noriega.12

The transition was precipitated by a series of escalating conflicts:
* Electoral Fraud: In May 1989, Noriega annulled a presidential election that the opposition candidate, Guillermo Endara, had won by a wide margin.31
* Political Repression: Noriega’s forces brutally assaulted opposition figures, and he declared a "state of war" with the United States in December 1989.31
* Military Intervention: Following the killing of a U.S. soldier, President George H.W. Bush ordered an invasion on December 20, 1989, to protect American lives, restore Panamanian liberties, and apprehend Noriega on drug-trafficking charges.1

On the first day of the invasion, Endara was sworn in as president. Noriega eventually surrendered to U.S. authorities on January 3, 1990, marking the end of his dictatorship and the beginning of a transition to democratic governance.31