Washington DC - Homeland Security Secretary Kristi Noem said Monday that Venezuela's Nicolas Maduro needs to be "gone" from power, in one of the clearest indications yet that Washington is seeking a change of leadership in Caracas.

President Donald Trump announced a blockade of "sanctioned oil vessels" sailing to and from Venezuela earlier this month, and Washington's forces have seized two ships and pursued a third so far.

Referring to those efforts, Noem told Fox News that "we're not just interdicting these ships, but we're also sending a message around the world that the illegal activity that Maduro's participating in cannot stand, he needs to be gone."

Washington has piled pressure on Maduro in other ways this year, accusing him of leading the alleged "Cartel of the Suns" – which it has declared a "narco-terrorist" organization – and offering a $50 million reward for information leading to his capture.

The US also amassed a huge flotilla of warships in the Caribbean – including the world's largest aircraft carrier – and has repeatedly flown military aircraft along Venezuela's coast in recent weeks.

US forces have also carried out a series of strikes targeting alleged drug-smuggling boats in the Caribbean and eastern Pacific that have destroyed nearly 30 vessels and left at least 104 people dead.

The US government has not provided conclusive evidence showing that the targeted vessels were carrying narcotics, and international law experts have said the strikes are likely illegal.

The Trump administration has insisted the goal of the strikes is curbing trafficking, but White House Chief of Staff Susie Wiles told Vanity Fair magazine the strikes are aimed at pressuring Venezuela, saying the US president "wants to keep on blowing boats up until Maduro cries uncle."