The Kremlin says Russian President Vladimir Putin has called US President Donald Trump to thank him for a CIA tip that has helped thwart a series of bombings in St Petersburg.
The Kremlin said Mr Putin told Mr Trump during the call that the information provided by the CIA was sufficient to track down and detain a group of suspects that was planning to bomb the Kazan Cathedral and other sites in the city.
The Kremlin says the Russian leader asked Mr Trump to convey his gratitude to the CIA and said Russian law enforcement agencies will hand over any information they get about potential terror threats against the United States, as they have done in the past.
The conversation is the second phone call between the two leaders since Thursday.
The Federal Security Service (FSB) announced on Friday that seven suspected followers of the Islamic State group had been arrested for allegedly planning to carry out terror attacks in St Petersburg this weekend.
The agency said the suspects were plotting a suicide bombing in a church and a series of other explosions in the city's busiest areas this coming weekend on IS orders. It said a search of a St Petersburg apartment found explosives, automatic weapons and extremist literature.
Russian news reports said that the Kazan Cathedral was the prime target.
Russian TV stations ran footage of FSB operatives outside an apartment building detaining a suspect, who was later shown confessing that he was told to prepare homemade bombs rigged with shrapnel.
The reports included footage of a metal container, which the suspects used as a laboratory for making explosives, according to the FSB. Another video showed operatives breaking the doors and raiding an apartment used by other suspects.
Last week, the FSB said it also arrested several IS-linked suspects in Moscow, where they allegedly were plotting a series of suicide bombings over New Year's.
In April, a suicide bombing in the St Petersburg's subway left 16 dead and wounded more than 50.