No Russian 'muscle movements' after Putin's nuclear readiness alert, U.S. says

FILE PHOTO: Russian President Vladimir Putin visits the construction site of the National Space Agency on the premises of the Khrunichev State Research and Production Space Centre, in Moscow, Russia February 27, 2022. Sputnik/Sergey Guneev/Kremlin via REUTERS/File Photo

WASHINGTON (Reuters) -The United States still has not seen any "muscle movements" following Russian President Vladimir Putin's weekend announcement that he was putting his nuclear forces on high alert, a senior U.S. defense official said on Monday.

But some former U.S. officials and experts caution that it would be a mistake to write off Putin's remarks as bluster, given the risk that Putin could decide to escalate to using nuclear weapons if he feels cornered over the war in Ukraine or if the war spills over into NATO.