Trump also pointed to China's growing influence around the canal, which connects the Atlantic and Pacific oceans.
US President-elect Donald Trump has threatened to close the Panama Canal after criticizing Panama for charging high tariffs on US ships that pass through the world's busiest waterway.
“Our navy and businessmen have been treated unfairly and unfairly. The money being paid by Panama is ridiculous,” Trump wrote on his Truth Social platform on Saturday.
The total “destruction” of our Earth will end immediately.
The US built the canal in 1914 and controlled the area around the canal for many years. But Washington ceded full control of the canal to Panama in 1999 after a period of joint administration.
Trump also pointed to China's growing influence around the canal, which connects the Atlantic and Pacific oceans.
“It was for Panama to manage, not China, or anyone else,” he said. “We cannot and will not allow it to fall into the wrong hands!”
The memo was a rare example of a US leader saying he could push an independent country to surrender.
“It was not given to help others, but as a sign of cooperation between us and Panama. If the ethical and legal principles of this handover are not followed, then we will demand that the Panama Canal be returned to us, in full, and without doubt,” Trump said.
Trump's tariff plan
It also reflects an expected shift in US diplomacy under Trump, who has not hesitated to threaten allies and use rhetoric in dealing with allies.
Last month, Trump said he would imposes tariffs on Mexican and Canadian goods on the first day of the administration and that the measures will remain in place until the “invasion” of immigrants and drugs ends.
“Mexicans and Canadians have all the right and power to solve this problem that has been growing. Here we ask them to use this power, and until the time they use it, it is time to pay the biggest price!” he wrote on his Truth Social page.
Officials in Panama did not react to Trump's comments.
About 5 percent of the world's maritime traffic passes through the Panama Canal, which allows ships traveling between Asia and the US East Coast to avoid the long, dangerous route around southern South America.
The Panama Canal Authority said in October that the canal had earned about $5bn in revenue in the last financial year.