WASHINGTON (AP) — President Donald Trump said Tuesday he is ordering a blockade of all “sanctioned oil tankers” into Venezuela, ramping up pressure on the country’s authoritarian leader Nicolás Maduro.

The moves comes after U.S. forces last week seized an oil tanker off Venezuela’s coast, an unusual move that followed a buildup of military forces in the region. In a post on social media Tuesday night announcing the blockade, Trump alleged Venezuela was using oil to fund drug trafficking and other crimes and vowed to escalate the military buildup.

“Venezuela is completely surrounded by the largest Armada ever assembled in the History of South America,” Trump said in a post on his social media platform. “It will only get bigger, and the shock to them will be like nothing they have ever seen before — Until such time as they return to the United States of America all of the Oil, Land, and other Assets that they previously stole from us.”

The buildup has been accompanied by a series of military strikes on boats in international waters in the Caribbean and eastern Pacific. The campaign, which has drawn bipartisan scrutiny among U.S. lawmakers, has killed at least 95 people in 25 known strikes on vessels.

The Trump administration has defended it as a success, saying it has prevented drugs from reaching American shores, and they pushed back on concerns that it is stretching the bounds of lawful warfare.

The Trump administration has said the campaign is about stopping drugs headed to the U.S., but Trump’s chief of staff Susie Wiles appeared to confirm in a Vanity Fair interview published Tuesday that the campaign is part of a push to oust Maduro.

Wiles said Trump “wants to keep on blowing boats up until Maduro cries uncle.”