China is increasing its purchases of Russian natural gas from a project under U.S. sanctions, a move that strengthens its energy partnership with Moscow and puts Washington on edge.

A sanctioned Russian tanker, Zarya, recently delivered liquefied natural gas (LNG) from the Arctic LNG 2 project to the Beihai terminal in southern China. It was at least the third shipment in recent weeks, according to ship-tracking data.

The U.S. blacklisted Arctic LNG 2 in 2023 to cut off funding for Russia’s war in Ukraine, but China has now become Russia’s top gas buyer, offsetting the loss of European customers. Beijing has also approved plans for the Power of Siberia 2 pipeline, which would bring even more Russian gas into the country.

Experts say these moves show China is willing to test U.S. and European sanctions. Chinese officials insist their energy choices are guided by national interests, while Ukraine continues to call on the world to halt all Russian energy trade.

Donald Trump, who has vowed to end the war quickly if he returns to the White House, has signaled he will push tougher trade measures against countries that continue buying from Moscow.