Panamanian officials offer concessions on Rubio’s first overseas stop, but say they cannot negotiate on control of the waterway.

Marco Rubio said he was hopeful after a visit that Panama would adequately address US concerns over Chinese influence in the Panama Canal.

Trump has refused to back down on threats to seize the vital waterway and it remains unclear what Rubio can achieve diplomatically that would please him, with Panama firmly rejecting any claims against its sovereignty.