Russia's security service the FSB have detained seven people said to be supporters of so-called Islamic State after acting on intelligence supplied by America's CIA.
The rare show of cooperation between the two countries has now been confirmed by the US's intelligence agency.
Explosives and weapons were found during the arrests - the suspects are said to have been of Dagestan and Tajikistan origin.
The White House released a statement after Russian President Vladimir Putin called President Donald Trump reportedly to thank him. It said "it showed what positive things can occur when the two countries work together".
The suspects are said to have been preparing to bomb St.Petersburg's Kazansky Cathedral and other areas in Russia's second city where large numbers of people gather.
Sunday's conversation between the two leaders marks the second time the two men have men have spoken in a week. On Thursday they are said to have discussed North Korea.
Until now relations between Washington and Moscow have been dominated by disagreements over the wars in Ukraine and Syria.