US Defense Secretary Pete Hegseth announced Thursday a military operation to "remove narco-terrorists," amid growing concerns that a US naval build-up in Latin American waters could presage land strikes and a wider conflict.

"Today, I'm announcing Operation SOUTHERN SPEAR," Hegseth posted on X. "This mission defends our Homeland, removes narco-terrorists from our Hemisphere, and secures our Homeland from the drugs that are killing our people."

The post gave no details of what the operation would entail or how it might differ from military actions already being undertaken.

President Donald Trump's administration is conducting a military campaign in the Caribbean and eastern Pacific, deploying naval and air forces for what it calls an anti-drugs offensive.

US forces have carried out strikes on about 20 vessels in international waters in the region since early September, killing at least 76 people, according to US figures.

Asked for clarification on the precise nature of Operation Southern Spear, a Pentagon spokesperson simply referred inquiries back to Hegseth's post on X.

CBS News on Wednesday cited multiple sources as saying senior military officials had presented Trump with updated options for potential operations in Venezuela, including strikes on land.

Venezuela announced Tuesday what it called a major, nationwide military deployment to counter the growing US naval presence off its coast -- including a newly arrived US aircraft carrier strike group in the region.

Caracas fears the deployment, which also includes F-35 stealth warplanes sent to Puerto Rico and six US Navy ships in the Caribbean, is a regime change plot in disguise.