Some U.S. lawmakers and officials are touting a nearly half-century-old treaty between the United States and Panama to justify the Trump administration's threat to reclaim the Panama Canal - provided it can show the strategic waterway's operation is under threat.

The U.S. has voiced concerns over Chinas growing influence around the Panama Canal, with Mauricio Claver-Carone, U.S. special envoy for Latin America, warning of national security risks. His remarks come ahead of U.

Secretary of State Marco Rubio said on Thursday he had "zero doubt" that China has a contingency plan to shut down the Panama Canal in the event of a conflict with the U.S. and that Washington intends to address what it sees as a national security threat.