US President Donald Trump has issued a blunt warning to NATO allies, insisting that Washington will only impose “major” sanctions on Russia if all member nations commit to doing the same — and completely stop buying Russian oil.

In a letter shared on social media Saturday, Trump said the next steps rest on NATO’s full cooperation.

“I am ready to do major Sanctions on Russia when all NATO Nations have agreed, and started, to do the same thing, and when all NATO Nations STOP BUYING OIL FROM RUSSIA,” Trump wrote. “NATO’S commitment to WIN has been far less than 100%, and the purchase of Russian Oil, by some, has been shocking! It greatly weakens your negotiating position, and bargaining power, over Russia. Anyway, I am ready to ‘go’ when you are. Just say when?”

Trump also urged NATO countries to hit China with sweeping tariffs as part of a broader strategy to pressure Moscow.

“I believe that this, plus NATO, as a group, placing 50% to 100% TARIFFS ON CHINA — to be fully withdrawn after the WAR with Russia and Ukraine is ended — will also be of great help in ENDING this deadly, but RIDICULOUS, WAR,” he added.

The president argued that such coordinated measures would “rapidly” force Russia to end its war in Ukraine.

The EU has already banned maritime imports of Russian oil and refined products, but several member states — and non-EU NATO allies like Turkey — still rely on Russian energy. Trump has also turned up the pressure on India, doubling tariffs on Indian imports to 50% over its continued Russian oil purchases, a move he acknowledged has “caused a rift” with New Delhi.

European leaders, however, have been cautious about following Trump’s lead, particularly on China tariffs, as Brussels continues to negotiate a major trade agreement with Beijing.

Trump’s demands come amid rising tensions along NATO’s eastern flank. Over the weekend, Romania’s defense ministry reported intercepting a drone that entered its airspace during Russian strikes on Ukraine. The device was tracked by two F-16s before disappearing near Chilia Veche, close to the Danube River.

Ukrainian President Volodymyr Zelensky condemned the incursion, calling it “an obvious expansion of the war by Russia” and noting that the drone operated in NATO airspace for nearly an hour. The incident follows a similar breach of Polish airspace earlier in the week, prompting NATO to strengthen its eastern defenses.

US Secretary of State Marco Rubio called the incursions “unacceptable and dangerous,” while Polish forces launched aviation operations as a precaution.

Trump’s ultimatum now looms large over NATO, threatening to deepen divisions among allies at a time when unity is being tested by Russia’s increasingly provocative actions.