WASHINGTON (AP) — Within a week of Donald Trump’s election, Sen. Lindsey Graham counseled the president-elect to quickly send a message to the drug cartels from the White House.

“Blow up something,” Graham told Trump.

The brazen military strike on a suspected drug-smuggling speedboat carrying 11 people from Venezuela this month is just what the South Carolina senator had in mind. But it has cleaved fresh divisions within the Republican Party over Trump’s campaign promise to keep the U.S. out of foreign entanglements and the reality of a commander in chief whose America First agenda is pursuing a tougher military stance.

And it’s raising stark questions about just how far Trump intends to wield his presidential power over the U.S. military without a robust check on the executive branch from Congress.

Already, Trump has dropped 30,000-pound (13,600-kilogram) bombs on Iran’s nuclear sites without any new authorizations from Capitol Hill. He deployed the military to Los Angeles over the objections of California’s Democratic governor and wants the National Guard in other cities, too. Trump’s allies pressured senators to confirm Pete Hegseth as defense secretary despite objections to his past behavior and skepticism of “warrior culture” at the Pentagon. And last week Trump rebranded the Department of Defense as the Department of War.

“I don’t care whether it’s a Republican president or a Democrat president,” said Republican Sen. Rand Paul of Kentucky, once a Trump rival for the White House. “We can’t just want to kill people without having some kind of process.”

“We’re just going to blow up ships? That just isn’t who we are,” Paul said.

‘Killing cartel members’

The Trump administration, and the president himself, have said the lethal strike on the vessel from Venezuela was intended to make it clear that the U.S. would not tolerate drugs being shipped into this country. They said those killed on the boat in the Caribbean included members of the Tren de Aragua gang, which operates from Venezuela, though details have been scarce.

“Killing cartel members who poison our fellow citizens is the highest and best use of our military,” Vice President JD Vance posted on social media.

When a prominent commenter suggested that killing civilians without due process would be a war crime, Vance replied that he didn’t care “what you call it.”

Paul, the senator, responded to Vance with his own questions.

“Did he ever read To Kill a Mockingbird?” Paul wrote. ”Did he ever wonder what might happen if the accused were immediately executed without trial or representation??

“What a despicable and thoughtless sentiment it is to glorify killing someone without a trial.”

A bipartisan briefing on the matter for the Senate’s top national security staff was abruptly canceled last week. And Tuesday’s rescheduled session left many questions unanswered.

‘There’s a legal way to do that’

The Trump administration did not explain its authority for the strike and would not provide legal opinion, according to a person familiar with the briefing who insisted on anonymity because it was closed.

“Where is the legality here?” said Sen. Mark Kelly, D-Ariz., a former Navy combat pilot and astronaut.

“I understand the need for us to be able to take out drug dealers from being able to deliver drugs into the United States,” he said. ”There’s a legal way to do that.”

But Kelly said he worries for the military officers involved with the mission. “What situation did we, did the White House, just put them in?” he said. ”I don’t know if this was legal or not.”

What Venezuela had to say

After Trump announced the strike, Venezuelan state television showed Venezuelan President Nicolás Maduro and first lady Cilia Flores walking the streets of his childhood neighborhood. A television presenter said Maduro was “bathing in patriotic love” as he interacted with supporters.

Maduro did not immediately address the strike directly but charged that the United States was “coming for Venezuela’s riches,” including the world’s largest proven oil reserves.

Trump’s national security vision and the power to enact it

Republicans have been shifting their national security priorities since Trump’s first term moved the GOP away from its traditional mooring as a party with a muscular approach to confronting adversaries and assisting allies abroad.

Trump’s America First approach initially launched a new era of U.S. neo-isolationism more aligned with the libertarian-leaning Paul than traditional defense hawks like Graham.

But in his second term, Trump is testing not his national security vision but his power to enact it.

Sen. Jim Risch of Idaho, the Republican chairman of the Senate Foreign Relations Committee, said he is “extremely confident” that the target of the boat bombing was “a group of narco-terrorists.”

“I can’t tell you how many lives were saved by the president of the United States when he pulled the trigger on that,” Risch said Tuesday. “There were tons of drugs that went down with that that would’ve wound up right here in the USA.”

Gesturing to the Supreme Court building across from the Capitol, GOP Sen. Josh Hawley of Missouri said he believes the president’s actions fall under his Article II authority, since the administration said the drugs were heading to the U.S.

“My gut intuition is it’s within the president’s commander in chief powers,” Hawley said.

Briefing for lawmakers

But Sen. Jack Reed of Rhode Island, the top Democrat on the Senate Armed Services Committee, called for lawmakers to receive a full briefing from the Trump administration, including the legal rationale for the military strike.

If the president exceeded his authority, then the Senate must consider all remedies available, including limiting the use of funds for further unauthorized military operations, he said. “We cannot risk the life of American servicemembers based on secret orders and dubious legal theories,” Reed said.

Graham, a former judge advocate general, or JAG, officer in the Navy, recalled his advice as Trump prepared to return to the White House.

“Whether it’s a lab, I don’t care if it’s in Mexico, I don’t care where it is,” Graham recalled. “I said, ‘Look for a target that changes the game.’”

Asked if the strike on the Venezuelan boat was it, Graham said: “Works for me.”