The United States Invasion of Panama, code-named Operation Just Cause, was the invasion of Panama by the United States in December 1989. It occurred during the administration of U.S. President George H. W. Bush, and ten years after the Torrijos–Carter Treaties were ratified to transfer control of the Panama Canal from the United States to Panama by 1 January 2000.

During the invasion, de facto Panamanian leader, general, and dictator Manuel Noriega was deposed, president-elect Guillermo Endara sworn into office, and the Panamanian Defense Force dissolved.

Local and international reactions

The invasion of Panama provoked international outrage. Some countries charged that the U.S. had committed an act of aggression by invading Panama and was trying to conceal a new manifestation of its interventionist policy of force in Latin America.

On 29 December, the General Assembly of the United Nations voted 75–20, with 40 abstentions, to condemn the invasion as a flagrant violation of international law.

On 22 December, the Organization of American States passed a resolution deploring the invasion and calling for withdrawal of U.S. troops, as well as a resolution condemning the violation of the diplomatic status of the Nicaraguan Embassy in Panama by U.S. Special Forces who had entered the building. 

At the UN Security Council, after discussing the issue over several days, a draft resolution demanding the immediate withdrawal of U.S. forces from Panama was vetoed on 23 December by three of the permanent members of the Security Council, France, United Kingdom, and the United States, who cited its right of self-defense of 35,000 Americans present on the Panama Canal.

Peru recalled its ambassador from the U.S. in protest of the invasion.

Some claim that the Panamanian people overwhelmingly supported the invasion. According to a CBS poll, 92% of Panamanian adults supported the U.S. incursion, and 76% wished that U.S. forces had invaded in October during the coup. However, others dispute this finding, asserting that the Panamanian surveys were conducted in wealthy, English-speaking neighborhoods in Panama City, among Panamanians most likely to support U.S. actions. Human Rights Watch described the reaction of the civilian population to the invasion as "generally sympathetic".

In 2006, one author opined that "President Bush had not defended the hemisphere against European aggression under the guise of the Monroe Doctrine, or used the threat of Communist proliferation to take action, but instead he had used the US military to remove a hostile and problematic Latin American dictator from power because it was in the best interests of the United States to do so."

Eighteen years after the invasion, Panama's National Assembly unanimously declared 20 December 2007 to be a day of national mourning. The resolution was vetoed by President Torrijos.

According to Robert Pastor, a former U.S. national security advisor, 74% of Americans polled approved of the action. Studies by Jeff Cohen and others of Fairness and Accuracy in Reporting have attributed this support to the mainstream media's intentional exclusion of critical viewpoints from television reporting preceding the invasion.

The Washington Post disclosed several rulings of the Office of Legal Counsel, issued shortly before the invasion, in regards to the U.S. armed forces being charged with making an arrest abroad. One ruling interpreted the Executive Order against Assassination of Foreign Leaders, which prohibits the intentional killing of foreign leaders, as suggesting that accidental killings would be acceptable foreign policy. Another ruling concluded that the Posse Comitatus Act of 1878, which prohibits the armed forces from making arrests without Congressional authorization, is effective only within the boundaries of the U.S., such that the military could be used as a police force abroad—for example, in Panama, to enforce a federal court warrant against Noriega.