President Donald Trump said the U.S. military conducted a second strike on what he described as "violent drug trafficking cartels" from Venezuela, killing three people in international waters in an ongoing campaign that has raised bipartisan concerns about due process.

Trump said he ordered the strike and no U.S. forces were harmed. Those targeted were "transporting illegal narcotics," Trump said Sept. 15 in a social media post.

Republican and Democratic lawmakers questioned the tactics after an earlier strike on a suspected drug boat.

“What a despicable and thoughtless sentiment it is to glorify killing someone without a trial," U.S. Sen. Rand Paul, R-Kentucky, wrote online after Vice President JD Vance touted the earlier strike.

The U.S. military killed 11 alleged Tren da Aragua members aboard a suspected drug boat originating from Venezuela in the southern Caribbean on Sept. 2. Democrats wrote the Trump administration a letter Sept. 10 asking about the legal basis for the strike.

"We assert that Congress made no declaration of war nor did it authorize the use of military force for future similar operations," the letter reads. "Classifying a clear law enforcement mission as counterterrorism does not confer legal authority to target and kill civilians."

University of Notre Dame Law School professor Mary Ellen O'Connell, an expert on international law, described the latest strike as "unlawful killing" and said it "only sends the message that compliance with law doesn’t matter to the U.S.."

Pressed during a Sept. 15 White House event if he would provide proof that the individuals targeted in the latest strike were "narco-terrorists," Trump said "we have recorded proof and evidence."

Trump issued a warning that more strikes could be coming.

"IF YOU ARE TRANSPORTING DRUGS THAT CAN KILL AMERICANS, WE ARE HUNTING YOU!" he wrote on social media.

The strikes are a milestone in increasingly militarized U.S. counterdrug efforts in the region. Trump secretly authorized military force against drug cartels in early August.

Contributing: Davis Winkie and Josh Meyer

This article originally appeared on USA TODAY: Trump says 3 killed in second strike on alleged Venezuelan drug traffickers

Reporting by Zac Anderson, USA TODAY / USA TODAY

USA TODAY Network via Reuters Connect