Donald Trump has said he is "very angry" and "pissed off" with Russian President Vladimir Putin after weeks of attempting to negotiate a ceasefire in Ukraine.
In an NBC News interview, the US president said he was angry with Putin for attacking Ukrainian President Volodymyr Zelensky's credibility, and threatened to impose a 50% tariff on countries buying Russian oil if he did not agree to a ceasefire.
"If Russia and I are unable to make a deal on stopping the bloodshed in Ukraine, and if I think it was Russia's fault - which it might not be... I am going to put secondary tariffs... on all oil coming out of Russia," he said.
The comments mark a shift in Trump's tone toward Putin and Russia.
The White House did not immediately respond to a request for comment.
European leaders had worried that Trump was cosying up to Putin as negotiations on a ceasefire in Ukraine continued.