The Trump administration has frozen all Venezuelan government assets in a dramatic escalation of tensions with socialist leader Nicolas Maduro, who has stubbornly clung to power in the face of mounting international pressure.
The ban on Americans doing business with Venezuela’s government takes effect immediately.
An executive order signed by president Donald Trump justified the move by citing Mr Maduro’s continued “usurpation” of power and human rights abuses by groups loyal to him.
While the order falls short of an outright trade embargo, it represents the most determined US action to remove Mr Maduro since the Trump administration recognised opposition leader Juan Guaido as Venezuela’s rightful leader in January.
As such, it places Venezuela on par with adversaries such as Cuba, Syria, Iran and North Korea, who have also come under strident US measures.
A senior Russian politician has denounced the move as a crude interference in Venezuela’s internal affairs.
Konstantin Kosachev, the head of the Russian upper house’s international affairs committee, said the Trump administration’s action amounts to “international banditry”.
Russia strong backs Mr Maduro, while the US and dozens of other nations have cast their support behind opposition leader Juan Guaido, and recognised him as Venezuela’s interim president.
Previous sanctions have targeted dozens of Venezuelan government insiders as well as the South American nation’s oil industry, the source of almost all of its export earnings.
As part of the executive order, Americans will be banned from engaging in transactions with anyone determined to be assisting Mr Maduro or his government.
The same Maduro supporters will also be banned from entering the US.
Exceptions will be allowed for the delivery of food, medicine and clothing.
Transactions with Venezuela’s still sizeable private sector do not appear to be affected either.
The executive order comes the day before Mr Trump’s national security adviser John Bolton and US Commerce Secretary Wilbur Ross represent the United States at the International Conference for Democracy in Venezuela.
The conference is being attended by representatives from more than 50 nations that recognise Mr Guaido as Venezuela’s president and consider Mr Maduro’s re-election last year to be fraudulent.
Moments after the executive order was announced, Mr Bolton tweeted that he was looking ahead to what he hopes will be a “productive” day in Lima, Peru.