In December 1989, the US began ?Operation Just Cause? in Panama in order to remove dictator Noriega, after a U.S. Marine was shot dead at a Panamanian Defense Force (PDF) roadblock. The invasion was considered just in consideration of the threat to American citizens, human rights violations, high levels of drug trafficking, and the strategic importance of the Panama Canal. Nonetheless, many countries opposed the invasion and declared it a violation of international law. Following Noriega?s arrest in January 1990, the US began to withdraw its troops.