U.S. President Donald Trump has accused his Colombian counterpart, Gustavo Petro, of being an "illegal drug leader” and said the U.S. would halt all aid to the country, escalating tensions between the two nations.

Trump claimed drug trafficking "has become the biggest business in Colombia” and said Petro "does nothing to stop it” despite years of U.S. funding. "AS OF TODAY, THESE PAYMENTS... WILL NO LONGER BE MADE,” the U.S. president wrote Sunday on social media.

The announcement follows Trump’s September decision to "decertify” Colombia as a partner in fighting narcotics, relegating the longtime U.S. ally to the same category as Venezuela, Bolivia, Afghanistan and Myanmar. The move comes amid the largest cocaine boom in history, with most of the supply originating in Colombia, and threatens one of Washington’s closest security alliances in Latin America.