The 19th century term describes the perceived right of Americans to use force or the threat of force to wrest desireable land from the grasp of others.
The president-elect's undiplomatic talk in recent days of reclaiming the Panama Canal — and annexing Greenland and even Canada — have some experts comparing his strategy to Nixon's "Madman Theory."
Handing control of the Panama Canal from the U.S. over to the Central American country was one of President Jimmy Carter's most controversial, and most overshadowed, foreign policy achievements.
It's unclear how the issue of ownership of the Panama Canal became a talking point for President-elect Donald Trump this week, but the question has a long political history.
Panama has officially established diplomatic relations with China and will exchange ambassadors. The shift is a major win for China as it seeks to isolate Taiwan.
The expansion of the Panama Canal, a $5 billion project, opens next month and aims to triple the canal's capacity with bigger ships. A Chinese freighter will be the first one through the new locks.