US President Donald Trump sent a letter to NATO countries on Saturday urging them to stop buying Russian oil and impose major sanctions on Russia to end its war in Ukraine.

"I am ready to impose significant sanctions against Russia, provided that all NATO countries also decide to do so and that all NATO countries stop buying oil from Russia," he wrote on social media.

His proposal is for NATO, as a group, to impose tariffs of 50-100% on China to weaken its economic control over Russia. This follows Trump's previous threats to impose sanctions on Moscow and secondary sanctions on countries that buy its oil, such as major buyers China and India, if progress is not made in ending the war in Ukraine.