MOSCOW, December 23. /TASS/. The assistance from CIA in preventing a terrorist attack in St. Petersburg was not the only example of successful cooperation between the U.S. and Russian intelligence services, head of Russia’s Foreign Intelligence Service Sergey Naryshkin told TASS on Saturday.

"We estimate as positive the cooperation between the Russian and U.S. intelligence services," he said. "This cooperation is on a regular base, and this (prevention of the terrorist attack in St. Petersburg) is not the only episode."

"Of course, we cooperate in fighting terrorism, and we exchange information regularly," he added.

He chose not to reveal to reporters details of the data the CIA had provided to Russia on that case.

"It is a part of a big joint work," he said. "Cooperation between reconnaissance authorities, between security agencies of various countries, including our cooperation with counterparts in the United States continues quite constructively. Of course, there are reserves, but, nevertheless, we consider this work as positive," Naryshkin said. "It (sharing information) is quite a lot: to get timely information so that using it to continue thorough work further on," he said.

On December 17, the Russian President Vladimir Putin thanked his U.S. counterpart Donald Trump for the information provided by the Central Intelligence Agency (CIA), which helped detain terrorists planning to carry out explosions in the Kazan Cathedral and at other crowded sites in Russia’s St. Petersburg. "The information received from the CIA was enough to locate and detain the criminals," the Kremlin said then.