Russia will shift its policy on the "preventive" use of nuclear arms in the next version of its main military strategy document, a top Russian security official was quoted as saying Thursday.

"Changes in the positions on the option of carrying out preventive nuclear strikes will go into the new military doctrine," said Nikolai Patrushev, the secretary of the national security council, Russian news agencies reported.

It was not immediately clear whether Patrushev's comments meant that Russia would expand the number of situations in which it would consider the first use of nuclear weapons.

Under its current military doctrine, Russia says it would only carry out a nuclear strike if it were attacked with weapons of mass destruction or if it were the victim of "large-scale aggression" using conventional arms.

In the latter years of the Cold War, the Soviet Union said it would not use nuclear weapons unless it were hit first with an atomic attack.

Since the 1991 Soviet collapse, however, Russian military planners have relied more on the country's huge nuclear deterrent as the size of Russia's army and the capabilities of its conventional forces have dwindled.

In recent years officials have been preparing a new version of Russia's official military doctrine.

"Our new military doctrine will be open, so that everyone, both at home and abroad, knows how we develop our positions on security," Patrushev told reporters in the Siberian city of Novosibirsk.

Before becoming head of the security council, Patrushev was head of Russia's powerful FSB security service, the successor to the Soviet-era KGB.