The European Union's latest effort to restrict Russia's oil revenue is unlikely to hurt Moscow's war effort severely, leaving U.S. President Donald Trump's threat of secondary sanctions one of the few remaining economic levers to pressure the Kremlin.

Oil prices declined in early Asian trading on Tuesday as markets assessed that European sanctions on Russia would have a minimal effect on global supply. At the same time, growing concerns over a potential trade dispute between the United States and the European Union also weighed on prices.