President-elect Donald Trump on Saturday accused Panama of charging excessive rates for use of the Panama Canal and said that if Panama did not manage the canal in an acceptable fashion, he would demand the US ally hand it over.

In an evening post on Truth Social, Trump also warned he would not let the canal fall into the “wrong hands,” and he seemed to warn of potential Chinese influence on the passage, writing the canal should not be managed by China.

The post was an exceedingly rare example of a US leader saying he could push a sovereign country to hand over territory. It also underlines an expected shift in US diplomacy under Trump, who has not historically shied away from threatening allies and using bellicose rhetoric when dealing with counterparts.

The United States largely built the canal and administrated territory surrounding the passage for decades. But the US government fully handed control of the canal to Panama in 1999 after a period of joint administration.

“The fees being charged by Panama are ridiculous, especially knowing the extraordinary generosity that has been bestowed to Panama by the US,” Trump wrote in his Truth Social post.

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