Russia’s President Vladimir Putin has thanked US counterpart Donald Trump for intelligence that helped foil “acts of terrorism” on Russian soil, according to a Kremlin statement.
Mr Putin and Mr Trump spoke on the phone on Sunday, it said.
The Kremlin said the information came via intelligence services, but it provided no further details.
Russian media is reporting the discovery of a plot to attack St Petersburg over the new year period.
Tass news agency says two Russian nationals have been arrested and plans to attack a mass gathering were seized, according to a spokesperson from the FSB, the Russian intelligence agency.
Mr Putin and Mr Trump have spoken on the phone and in person various times since the latter took office.
Records from the conversations show they have often talked about Syria, as well as nuclear agreements, North Korea and trade.
In December 2017, Mr Putin thanked Mr Trump for another warning from US intelligence agencies, which again apparently prevented a terrorist plot in St Petersburg, according to a White House account.