The Trump administration decreed sanctions against Venezuelan Vice President Tareck El Aissami on Monday, accusing him of playing a major role in international drug trafficking.



The announcement, made on the Treasury Department's website late in the day, is bound to ratchet up tensions between the U.S. and its harshest critic in Latin America. El Aissami is the most senior Venezuelan official to ever be targeted by the U.S.



The U.S. government is also sanctioning Samark Lopez, a wealthy Venezuelan businessman believed to be El Aissami's main front man. As part of the action, 13 companies owned or controlled by Lopez, including five in Florida, will be blocked and both men will be barred from entering the United States.



There was no immediate reaction from El Aissami, but he has long denied any criminal ties.



The move comes a week after a bipartisan group of 34 U.S. lawmakers sent a letter to Trump urging him to step up pressure on Venezuela's socialist government by immediately sanctioning top officials responsible for corruption and human rights abuses as well as El Aissami for his purported ties to Hezbollah.



In the wake of President Nicolas Maduro's crackdown on dissent following anti-government protests in 2014, the U.S. Congress passed legislation authorizing the U.S. president to freeze the assets and ban visas for anyone accused of carrying out acts of violence or violating the human rights of those opposing Venezuela's government. Monday's sanctions were imposed under rules passed during the Clinton administration allowing the U.S. to go after the assets of anyone designated a drug kingpin.



El Aissami, 42, has been the target of U.S. law enforcement investigation for years, stemming from his days as interior minister when dozens of fraudulent Venezuelan passports ended up in the hands of people from the Middle East, including alleged members of Hezbollah.



Venezuela's top convicted drug trafficker, Walid Makled, before being sent back from Colombia in 2011, said he paid bribes through El Aissami's brother to officials so they could turn a blind eye to cocaine shipments that have proliferated in Venezuela during the past two decades of socialist rule.



El Aissami was named vice president last month as Maduro struggles to hold together a loose coalition of civilian leftist and military supporters whose loyalty to the revolution started by the late Hugo Chavez has frayed amid triple-digit inflation and severe food shortages. Recent polls say more than 80 percent of Venezuelans want Maduro gone.



El Aissami is feared by many in the opposition for his association with Venezuela's intelligence services from his long run as interior minister under Chavez. Since El Aissami became vice president, Maduro has handed him control of an "anti-coup commando unit" to go after officials and opponents suspected of treason.



A former Obama administration official said the decision to sanction El Aissami was months in the making and involved several U.S. federal agencies. But it was held up last year, at the insistence of the State Department, for fear it could interfere in a Vatican-backed attempt at dialogue between the government and opposition as well as efforts to win the release of a U.S. citizen, Joshua Holt, jailed for months on what are seen as trumped-up weapons charges.



"This was an overdue step to ratchet up pressure on the Venezuelan regime and signal that top officials will suffer consequences if they continue to engage in massive corruption, abuse human rights and dismantle democracy," said Mark Feierstein, who served as Obama's top national security adviser on Latin America.



The talks between the opposition and Venezuela have since collapsed. The opposition blames Maduro's administration, saying it didn't follow through on a pledge to release dozens of activists that government opponents consider political prisoners. The opposition also says Maduro didn't set a date for regional elections that his opponents are favored to sweep after the government suspended a recall referendum against the president in October.



"The sanctions in and of themselves will not bring about a democratic transition," Feierstein said. "That will require the Venezuelan opposition to remobilize its followers and U.S. diplomatic efforts to marshal governments in the region to isolate Maduro."



Tensions between the U.S. and Venezuela have been on the rise for years. The countries haven't exchanged ambassadors since 2010.



But Trump mentioned the country only briefly during the campaign, and amid uncertainty on whether he would break from the Obama administration's policy of relative restraint, Maduro had adopted a softer tack. After blasting Trump as a "bandit" and "mental patient" during the campaign, Maduro has remained quiet since.



"He won't be worse than Obama, that's the only thing I dare to say," Maduro said last month in an appeal to supporters to withhold judgment on Trump.



In the wake of a travel ban against top Venezuelan officials in 2014, Maduro ordered the U.S. to slash staffing at its embassy in Caracas, accusing diplomats of conspiring to overthrow his government.