President Donald Trump has delivered an ultimatum to America's European allies to fix the "terrible flaws" in the Iran nuclear deal, or he'll pull the U.S. out in a few months' time.

Trump made the threat Friday as he extended waivers of key economic sanctions on Iran, keeping the accord alive at least for now. But his explicit warning to Europe that the deal must be fixed by the time the next sanctions waivers are due in the spring creates a high-stakes diplomatic deadline that will be difficult to meet.

Trump's declaration puts great pressure on Britain, France and Germany, the European signatories to nuclear pact with Iran. Trump wants them to help the U.S. devise a new agreement designed to prevent Iran from escalating nuclear activity again next decade.