Putin approves revision of 'nuclear doctrine'... to be used even for non-nuclear states supported by nuclear states.

Russian President Putin has approved a revision of Russia's nuclear doctrine that includes the principle of using nuclear weapons, with the United States allowing the use of long-range missiles to strike the Russian mainland.

Tas news agency says Putin has signed a presidential decree authorizing the revised nuclear doctrine.

The new nuclear doctrine goes into effect today.

According to an open nuclear doctrine document, even countries that do not possess nuclear weapons would consider Russia a joint attack with the support of nuclear powers.

It is aimed at Ukraine, which is supported by the U.S., the U.K., and France, which are nuclear powers.

"If Ukraine uses Western non-nuclear missiles, a nuclear response could follow," Kremlin spokesman Dmitry Peskov warned at a briefing.

Russia also stated the right to consider a nuclear response in the event of conventional weapons attacks threatening its sovereignty, mass launches of aircraft and missiles, and attacks on its ally Belarus.

Earlier, at a national security meeting in September, Putin said, "The policy in the field of nuclear deterrence should be adjusted to suit reality," signaling an expansion of the scope of nuclear weapons use.

Russian Foreign Ministry spokesman Mariya Zakharova also warned that allowing U.S. long-range missile strikes would mean direct involvement in the conflict and that "Russia's response would be appropriate and obvious."