US President Donald Trump has said that the airspace around Venezuela should be considered closed.

To all Airlines, Pilots, Drug Dealers, and Human Traffickers, please consider THE AIRSPACE ABOVE AND SURROUNDING VENEZUELA TO BE CLOSED IN ITS ENTIRETY, Trump said in a social media post.

The US does not legally have the authority to close another country's airspace, but Trump's post could lead to travel uncertainty and deter airlines from operating there.

The US has been building its military presence in the Caribbean, which officials say is to combat drug smuggling. Venezuela's President Nicolás Maduro has dismissed US claims of drug trafficking as an attempt to oust him.

Venezuela has not yet responded to Trump's remarks. The White House did not immediately respond to the BBC's request for comment.

Trump's comments come days after the US Federal Aviation Administration (FAA) warned airlines of heightened military activity in and around Venezuela.

On Wednesday, Venezuela banned six major international airlines – Iberia, TAP Portugal, Gol, Latam, Avianca and Turkish Airlines – from landing there after they failed to meet a 48-hour deadline to resume flights.

The US has deployed the world's largest aircraft carrier, the USS Gerald Ford, and about 15,000 troops to within striking distance of Venezuela, insisting that the deployment is to combat drug trafficking.

On Thursday, Trump warned that US efforts to halt Venezuelan drug trafficking by land would begin very soon. US forces have carried out at least 21 strikes on boats they said were carrying drugs, but have not provided evidence that the boats carried drugs.

The Venezuelan government believes the aim of the US action is to depose Maduro, whose re-election last year was denounced by the Venezuelan opposition and many foreign nations as rigged.

The US has also designated Cartel de los Soles, which it alleges is headed by Maduro, as a foreign terrorist organization.

Labeling an organization as a terrorist group gives US law enforcement and military agencies broader powers to target and dismantle it. Venezuela's foreign ministry has categorically, firmly, and absolutely rejected the designation.