Operation Just Cause was the invasion of Panama by the United States, taking place between December 20 1989 and January 31 1990

10 Years after thee Torrijos-Carter Treaties were ratified transferring control of the Panama Canal from the U.S. to Panama by 2000. The invasion resulted in in the then current Panamanian leader A dictator named Manuel Noriega being deposed and replaced with President Elect Guillermo Endara, and the Panamanian Defence force being dissolved.

In 1986 Ronald Reagan attempted to negotiate with Noriega, requesting that he step down peacefully after being exposed in the Iran Contra Affair. Noriega was pressured with drug related indictments. Extradition laws between Panama and the U.S. however were weak, and Noriega thought the threat to lack credibility. After May of 1989 when Endara was elected president, defeating Noriega's preferred man Noriega supporters attacked Endara's motorcade and beat him. Noriega declared the election Null and took over Panama as a dictatorship. The Panamanian people called for Noriega to step down. President George Bush Sr called on Noriega to honor the will of the people. After refusing, Bush was pressured for being too weak to handle such matters, Bush stated that the U.S. would not negotiate with a known drug trafficker. The Department of Defense claimed that Noriega was responsible for unable servicement being shot and killed. This among other incidents opened the door for the U.S. to invade Panama.

The official United States justification for the invasion was articulated by President Bush on the morning of 20 December 1989, a few hours after the start of the operation. President Bush listed four reasons for the invasion:[21] Safeguarding the lives of U.S. citizens in Panama. In his statement, Bush claimed that Noriega had declared that a state of war existed between the United States and Panama and that he also threatened the lives of the approximately 35,000 US citizens living there. There had been numerous clashes between U.S. and Panamanian forces; one US Marine had been killed a few days earlier and several incidents of harassment of US citizens had taken place. Defending democracy and human rights in Panama. Combating drug trafficking. Panama had become a center for drug money laundering and a transit point for drug trafficking to the United States and Europe. Protecting the integrity of the Torrijos–Carter Treaties. Members of Congress and others in the U.S. political establishment claimed that Noriega threatened the neutrality of the Panama Canal and that the United States had the right under the treaties to intervene militarily to protect the Panama canal.