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.

Treaties ratified by the Senate in 1978 established permanent neutrality, but some Republicans regret that decision.

Trump named Miami-Dade County Commissioner Kevin Marino Cabrera as his choice for the post after suggesting that the US should take control of the Panama Canal – a proposal he first floated over the weekend while claiming that Panama is “ripping off” American ships that pass through the waterway.