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.

US senators heard sharply different analyses about Chinese influence over the Panama Canal on Wednesday, with some experts suggesting solutions ranging from enhanced trade partnerships to military intervention to regain control of the strategic waterway.

Jose Raul Mulino said he won't discuss control of the canal during the secretary of state's visit. Rubio, in contrast, said "we're going to address that topic."