President Donald Trump says his administration will brief Congress about the strikes on the alleged drug-carrying vessels as well as plans to shift to targets on land but he says he doesn't believe the administration needs a formal declaration of war.

"I don't think we're going to necessarily ask for a declaration of war. I think we're just going to kill people that are bringing drugs into our country," Trump said to reporters during a briefing with homeland security officials.

"We're going to kill them. They're going to be like, dead," he said.

The U.S. military on Wednesday launched its ninth strike against an alleged drug-carrying vessel, killing three people in the eastern Pacific Ocean, Defense Secretary Pete Hegseth said, expanding the Trump administration’s campaign against drug trafficking in South America.

It followed another strike Tuesday night, also in the eastern Pacific, that killed two people, Hegseth posted on social media hours earlier. The attacks were departures from the seven previous U.S. strikes that had targeted vessels in the Caribbean Sea.

They bring the death toll to at least 37 from attacks that began last month.

The strikes represent an expansion of the military's targeting area as well as a shift to the waters off South America where much of the cocaine from the world’s largest producers is smuggled.

Trump has justified the strikes by asserting that the United States is engaged in an “armed conflict” with drug cartels and proclaiming the criminal organizations unlawful combatants, relying on the same legal authority used by President George W. Bush's administration for the war on terrorism.

The president said the strikes at sea have been "so effective" that the U.S. will soon strike targets on land.

"You know, the land it's going be next, and we may go to the Senate, we may go to the, you know, Congress and tell them about it, but I can't imagine they'd have any problem with it," Trump said.

"I think, in fact, while we're here, I think it's a good idea, Pete. You go to Congress, you tell them about it. What are they going to do? Say, gee, we don't want to stop drugs pouring in," he added.

Lawmakers from both political parties have expressed concerns about Trump ordering the military actions without receiving authorization from Congress or providing many details.