President Trump says he is pulling all funding for the Colombian government’s anti-drug programs in an effort to get the country’s leader, President Gustavo Petro, to crack down more forcefully on drug production. Mr. Trump says that if Mr. Petro does not “close up” the sources of the drugs, “the United States will close them up for him.”

Of all the foreign leaders with whom Mr. Trump has tangled since returning to the White House in January, his spats with Mr. Petro have been especially ugly. In the first week of his second term, Mr. Trump hit Colombia with tariffs, sanctions, and visa restrictions after Mr. Petro refused to accept two migrant repatriation flights. Mr. Petro later relented and allowed the planes to land. 

Earlier this month, Mr. Petro accused Mr. Trump of creating a “war scenario” in the Caribbean with his bombings of alleged drug smuggling boats. “There is no war against smuggling; there is a war for oil and it must be stopped by the world. The aggression is against all of Latin America and the Caribbean,” Mr. Petro said on October 9. 

On Sunday, Secretary of Defense Pete Hegseth announced that the military had destroyed another alleged drug-smuggling boat in international waters. Mr. Hegseth says it was helmed by members of a far-left Colombian guerrilla group, Ejército de Liberación Nacional. Mr. Petro himself is a former left-wing guerrilla, though he was a member of the rival M-19 organization. 

Now, Mr. Trump says that Mr. Petro will be losing his foreign aid from the United States unless he cracks down on drug manufacturers. According to the most recent data from the DEA, Colombia supplies around 90 percent of the cocaine that enters the United States. 

“President Gustavo Petro, of Columbia, is an illegal drug leader strongly encouraging the massive production of drugs, in big and small fields, all over Columbia,” Mr. Trump wrote in a post on Truth Social on Sunday morning, incorrectly spelling the name of the country. “It has become the biggest business in Columbia, by far, and Petro does nothing to stop it, despite large scale payments and subsidies from the USA that are nothing more than a long term rip off of America.”

“The purpose of this drug production is the sale of massive amounts of product into the United States, causing death, destruction, and havoc,” the president added. 

“Petro, a low rated and very unpopular leader, with a fresh mouth toward America, better close up these killing fields immediately, or the United States will close them up for him, and it won’t be done nicely,” Mr. Trump threatened.

Mr. Petro rejected Trump’s accusations and defended his efforts to fight narcotics in Colombia. “Trying to promote peace in Colombia is not being a drug trafficker,” Petro said in a social media post. He suggested that Trump was being deceived by his advisers, described himself as “the main enemy” of drugs in his country and said Trump was being “rude and ignorant toward Colombia.”

The president’s retribution appears to be in response to Mr. Petro’s accusation that Mr. Trump committed “murder” against a Colombian national. Mr. Trump on Saturday announced that he ordered the military to take out an alleged “drug-carrying submarine” in the Caribbean. The strike left two survivors, both of whom are being sent home to their respective native countries of Ecuador and Colombia. 

The same day, Mr. Petro said the American military had actually destroyed a fishing boat that was adrift. 

“U.S. government officials have committed a murder and violated our sovereignty in territorial waters,” Mr. Petro wrote in a post on X. “Fisherman Alejandro Carranza had no ties to the drug trade and his daily activity was fishing. The Colombian boat was adrift and had its distress signal up due to an engine failure.”

Colombia currently receives more than $200 million in foreign aid from the United States government annually, though it is unclear if Mr. Trump will be cutting all of those funds or money designated only for narcotics controls. The United States spends more than $20 million in Colombia specifically on trying to tamp down on drug trafficking. 

Mr. Petro, however, is unlikely to yield to Mr. Trump’s demands. The Colombian president himself has called for the wholesale legalization of cocaine worldwide in an effort to dismantle the international drug trade. 

“Cocaine is illegal because it is made in Latin America, not because it is worse than whiskey,” Mr. Petro said earlier this year. “Scientists have analyzed this: cocaine is not worse than whiskey.” On a personal level, Mr. Petro also seems to have a deep disdain for Mr. Trump. On Saturday, the Colombian leader shared a video of a large “No Kings” protest that was taking place here in the United States, in an apparent attempt to mock Mr. Trump.