The Trump administration is poised to impose steep tariffs starting Wednesday on countries that import oil from Venezuela, in a move analysts said is unprecedented and will significantly increase global trade uncertainty.

Any country that buys oil from Venezuela will face 25% “secondary tariffs” on all of its trade with the United States, President Donald Trump said in a Truth Social post March 24. The levies go into effect April 2, Trump said in the post, though his executive order leaves the implementation to Secretary of State Marco Rubio’s discretion.

“If they buy their oil from Venezuela, they have to pay a 25% tariff to do business with the United States —that’s on top of existing tariffs,” Trump said during a March 24 press conference at the White House.

Trump’s secondary tariffs are “unprecedented and legally questionable, but that won’t prevent the administration from moving forward with them,” according to the consulting firm Rapidan Energy. The International Emergency Economic Powers Act has never been invoked to justify across-the-board tariffs against a country, according to Rapidan.