Before President Donald Trump announced on Saturday that the US had captured President Nicolás Maduro of Venezuela, the US military had launched one of the largest deployments of its forces to the Caribbean region in decades.

The US Southern Command said that about 15,000 troops were in the region by December. President Trump described them as a "massive armada". In August, he had secretly signed a directive to the Pentagon to begin using military force against Latin American drug cartels that his administration had deemed terrorist organisations.

Since the signing, the US had carried out 35 lethal strikes on boats that the administration said were carrying narcotics. The attacks have killed more than 100 people. Legal and military experts questioned the legality of the strikes. Congress has not authorised them, nor has it declared war on Venezuela.

Some Trump officials have said that the main goal of the increase in troops was to drive Maduro, Venezuela's authoritarian leader, from power. Hours before Trump announced the capture of Maduro and his wife, the Venezuelan government accused the US military of carrying out attacks in the capital, Caracas, and other parts of the country.

In recent months, the US military buildup has included transport and cargo planes. Flight-tracking data reviewed by The New York Times showed C-17 heavy-lift cargo planes — largely used for transporting military troops and equipment — conducted at least 16 flights to Puerto Rico from American military bases in one recent week. The C-17s flew to Puerto Rico from bases in New Mexico, Illinois, Vermont, Florida, Arizona, Utah, Washington State and Japan.

The US has also recently moved special-operations aircraft to the Caribbean.

Since October, the US forces have included a Navy expeditionary strike group consisting of amphibious warships carrying thousands of Marines, along with warplanes, attack helicopters and other aircraft.

The buildup also brought the arrival in November of a full aircraft carrier strike group, with the USS Gerald R. Ford and several destroyers loitering roughly 100 nautical miles off the shores of Venezuela.

The Ford and its air wing, however, have not been used to attack vessels suspected of smuggling drugs. Those attacks have been launched by drones and AC-130 gunships controlled by the US Joint Special Operations Command.

The US Coast Guard has also begun chasing, boarding and even seizing oil tankers that the White House says are violating sanctions on Caracas.