(Reuters) - The United States is considering transferring some troops stationed in Western Europe to Eastern Europe in the coming weeks, a NATO diplomat told Reuters, amid escalating tensions between Ukraine and Russia.

       "This has to do with American troops that are already in [Western] Europe," the diplomat said, speaking on condition of anonymity, confirming a New York Times report that said U.S. President Joe Biden was considering sending U.S. troops to the Baltics and Eastern European allies.

       NATO said on Monday it was putting forces on standby and reinforcing eastern Europe with more ships and fighter jets, in what Russia denounced as an escalation of tensions over Ukraine.

       The diplomat said the potential troop movements would be gradual and that any filling of NATO gaps on its eastern flank could take place in the coming weeks.

       (Editing by Jon Boyle and Gareth Jones)