They say they fought too hard to wrest it from the U.S. to now hand back the waterway, which is part of the nation’s identity.

The neutrality of the nearly 50-mile canal, through which nearly 15,000 ships transit each year, is enshrined in Panama’s Constitution and is enforced by the autonomous Panama Canal Authority.

U.S. Secretary of State Marco Rubio will visit Panama and four other countries in Central America and the Caribbean starting late next week during his first overseas trip as Washington's top diplomat, ...