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.

Russia warned President Trump on Tuesday against seizing the Panama Canal, after he reiterated his intent to take control of the strategic waterway in his second inaugural address Monday. “We expect that during the expected discussions between the leadership of Panama and US President Donald Trump on issues of control over the Panama Canal,

Trump has repeatedly threatened to take ownership of the critical maritime trade route — which the U.S. signed over to Panama in 1977 — calling it “vital” to American interests and refusing to rule out using military force in pursuit of his goal.