In a Thursday news conference, Mulino forcefully disputed the State Department claim that U.S. warships can transit the canal for free.
“I want to make it very clear to the country my absolute rejection of the statement from the State Department,” he said. “It is based on a falsehood.”
The State Department had claimed in a Wednesday post on X that U.S. ships can transit “without charge fees, saving the U.S. government millions of dollars a year.”
Panama Canal authorities quickly denied the claim in a separate post, but Mulino and other officials have said they are open to continuing dialogue with Washington.
Rubio met with Mulino earlier this week during his trip to Panama, the first country he visited as secretary of State. In the meeting, the two discussed Chinese influence in Panama and illegal migration.
Mulino also had a conversation this week with Defense Secretary Pete Hegseth.
Trump, who has decried China’s presence in Panama and high transit fees, has called for the U.S. to take control of the canal. He has also made similar claims for Greenland and Gaza, while suggesting Canada should become the 51st state.
Mulino announced he is scheduled to speak with Trump on Friday.
Dozens of U.S. Navy ships cross through the Panama Canal each year, making use of a key waterway connecting the Atlantic and Pacific oceans. American commercial ships also make up a big share of the traffic.
Ships are expected to pay anywhere from $300,000 to $1 million to transit the canal.
The U.S. built the canal in the early 20th Century but later handed it over to Panama.
