A US attack on a boat suspected of transporting illegal drugs has left four men dead in the eastern Pacific Ocean, US defence secretary Pete Hegseth announced on X on Wednesday.

"Earlier today, at the direction of President Trump, the Department of War carried out a lethal kinetic strike on yet another narco-trafficking vessel," Hegseth posted.

On Monday, US strikes on suspected drug-trafficking ships in the Pacific killed 14 people, according to Hegseth.

The latest strikes, which have come at the direction of the president, mark an escalation in what the White House has cast as a campaign to stop seaborne narcotics from entering the US via both the Pacific and Caribbean.

Hegseth's post included a video showing a vessel catching fire after being struck by US munitions.