President Trump said on Tuesday that the United States had carried out a strike against a boat carrying drugs and killed 11 “terrorists,” the administration’s latest military escalation in Mr. Trump’s war against Venezuelan drug cartels that he has blamed for bringing fentanyl into the country.

Mr. Trump offered few details about the strike during his news conference on Tuesday, but Defense Department officials and Secretary of State Marco Rubio said it had targeted a boat being operated by a “designated narco-terrorist organization.”

Late Tuesday afternoon, Mr. Trump posted more details on the social media site Truth Social. “Earlier this morning, on my Orders, U.S. Military Forces conducted a kinetic strike against positively identified Tren de Aragua Narco terrorists,” Mr. Trump wrote. He said the strike “occurred while the terrorists were at sea in International waters transporting illegal narcotics, heading to the United States.”

No American troops were harmed in the operation, he said.

Mr. Trump’s post was accompanied by a video of what appeared to be a speedboat cutting through the water, with a number of people on board. An explosion then appears to blow it up.

A senior U.S. official said a Special Operations aircraft — either an attack helicopter or an MQ-9 Reaper drone — carried out the attack on Tuesday morning against a four-engine speedboat loaded with drugs. U.S. surveillance aircraft and other sensors had been monitoring cartel maritime traffic for weeks before the strike, said the official, who spoke on the condition of anonymity to discuss operational details.

The strike is an astonishing departure from traditional drug interdiction efforts. A second senior U.S. official, also speaking on condition of anonymity, said there would be more such attacks against cartel boats.