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 thelate 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