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.

“The Panama Canal is considered a VITAL National Asset for the United States, due to its critical role to America’s Economy and National Security,” Trump wrote. “A secure Panama Canal is crucial for U.S. Commerce, and rapid deployment of the Navy, from the Atlantic to the Pacific, and drastically cuts shipping times to U.S. ports.”