U.S. President Donald Trump has taken aim at Russian President Vladimir Putin, saying the Kremlin leader has “let him down” over the ongoing war in Ukraine.

Speaking in London after a meeting with British Prime Minister Keir Starmer, Trump argued that Russia’s military campaign could be crippled if Western nations united to stop importing Moscow’s oil and gas.

“Very simply, if the price of oil comes down, Putin will have no choice but to step back from this war,” Trump said on Thursday.

The president stressed that while Washington is open to exploring new measures against Moscow, further U.S. intervention would depend on Europe and other Western partners cutting off Russian energy purchases — a move he described as the key to choking off the Kremlin’s war chest.

Trump’s remarks mark a rare public rebuke of Putin, a figure he has previously avoided criticizing directly. His call also underlines the tension between America’s push to end the conflict and the economic reliance of many European countries on Russian crude, even as sanctions bite.

By placing responsibility on Western governments to shift away from Russian energy, Trump signaled that economic pressure — not military escalation — will remain the cornerstone of his strategy to bring the war in Ukraine to an end.