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.

Others, however, say hurdles would loom for any bid to use the 1977 Panama Canal Neutrality Treaty, which took effect in 1999 and guarantees that the canal would remain neutral and open to all ships from all countries, as a pretext for the U.S. to seize it.

The 82-kilometer waterway's construction was completed by the U.S. in 1914, and since its return to the Central American nation in 1999, it has been controlled by the Panama Canal Authority, an autonomous agency overseen by the Panamanian government.