Donald Trump issued a troubling warning about the future of the Panama Canal on Saturday, calling the United States' current arrangement with Panama a "rip-off" in a pair of Truth Social posts.

In his posts, the president-elect threatened to take back the waterway if Panama continues to charge the U.S. "exorbitant prices" to use the passage, which is a critical maritime corridor for both American military operations and global commerce.

"Our Navy and Commerce have been treated in a very unfair and injudicious way," one Trump post read. "The fees being charged by Panama are ridiculous, especially knowing the extraordinary generosity that has been bestowed to Panama by the U.S. This complete 'rip-off' of our Country will immediately stop...."

The United States is the canal's top wayfarer, making up 72.5% of its traffic, according to 2021 data from the Panama Canal Authority.

The Panama Canal Authority charges boats and ships for their use of the channel, with tariff costs ranging from $0.50 to $300,000, depending on the size and purpose of the vessels.

While the U.S. initially shouldered the bulk of construction costs when the canal was built in the first two decades of the 20th century, control of the waterway was transferred to Panama in 1999, based on the terms of a 1979 treaty brokered by then-President Jimmy Carter.

Claiming Carter "foolishly" gave away the passage between the Pacific and Atlantic oceans, Trump then demanded control of the canal be returned to the U.S.

"It was not given for the benefit of others, but merely as a token of cooperation with us and Panama," he said.

"If the principles, both moral and legal, of this magnanimous gesture of giving are not followed, then we will demand that the Panama Canal be returned to us, in full, and without question," Trump continued. "To the Officials of Panama, please be guided accordingly!"

In his posts, Trump also indicated anger at China's growing presence at the Central American ocean corridor.

China is the canal's second biggest user but has not indicated any interest in purchasing the passage. A Hong Kong-based company does administer two of the waterway's five ports, however.