US President Donald Trump sent a letter to the NATO military alliance states, urging all members to stop buying Russian oil and to impose sanctions on Russia in order to end the war in Ukraine.

"I am ready to impose significant sanctions on Russia, when all NATO member states agree and start doing the same, and when all NATO member states stop buying oil from Russia," he said in a social media post.

He also suggested that NATO as a whole impose 50-100% tariffs on China in order to weaken its economic influence over Russia. The call follows Trump's previous threats of secondary sanctions against countries that buy Russian oil, such as top buyers China and India, if there is no progress towards ending the war in Ukraine.

I am ready to start [the sanctions] whenever you are ready. Just tell me when. I believe that this, combined with the fact that NATO, as a group, is imposing 50% to 100% tariffs on China, which will be completely removed after the end of Russia's war with Ukraine, will also contribute significantly to ending this deadly, but also ridiculous war, the US president said.

If NATO does what I say, the war will end soon and all these lives will be saved! If not, you are just wasting my time, as well as the time, energy and money of the United States, he added.