The legislation, which would allow the president to levy a 500% tariff on imports from countries that purchase Russian uranium, gas and oil, has gained momentum in the Senate as Trump has signaled he will escalate US action against Russia.

Russia and China's foreign ministers on Sunday discussed their relations with the United States and the prospects for ending the war in Ukraine, Russia's foreign ministry said in a statement.

North Korea's renewed military support for Russia comes as US President Donald Trump has resumed military supplies to Ukraine, after a brief hiatus. Trump told NBC News on Thursday that he had made a deal with Nato for the US to send Patriot air defence systems to Ukraine via the alliance, after a surge of Russian aerial attacks.