Incoming US president Donald Trump on Saturday slammed what he called unfair fees for US ships passing through the Panama Canal and threatened to demand control of the waterway be returned to Washington.
He also hinted at China's growing influence around the canal, a worrying trend for American interests as US businesses depend on the channel to move goods between the Atlantic and Pacific oceans.
"Our Navy and Commerce have been treated in a very unfair and injudicious way. The fees being charged by Panama are ridiculous," he said in a post on his Truth Social platform.
"This complete 'rip-off' of our Country will immediately stop."
The Panama Canal, which was completed by the United States in 1914, was returned to the Central American country under a 1977 deal signed by Democratic president Jimmy Carter.
Panama took full control in 1999.
"It was solely for Panama to manage, not China, or anyone else," Trump said. "We would and will NEVER let it fall into the wrong hands!"
He continued that if Panama could not ensure "the secure, efficient and reliable operation" of the channel, "then we will demand that the Panama Canal be returned to us, in full, and without question."
Authorities in Panama did not immediately react to Trump's post.
Although he does not officially take office until next month, Trump has nevertheless been flexing his political influence in the waning days of President Joe Biden's administration.
The real estate mogul boasted on the campaign trail that as an entrepreneur, he was uniquely positioned to fight for US business interests.
An estimated five percent of global maritime traffic passes through the Panama Canal, which allows ships traveling between Asia and the US East Coast to avoid the long, hazardous route around the southern tip of South America.
The main users of the passage are the United States, China, Japan and South Korea.
The Panama Canal Authority reported in October that the waterway had earned record revenues of nearly $5 billion in the last fiscal year.