Moscow - Russia reserves the right to use nuclear weapons in response to a conventional strike and sees them as a "great equaliser" reducing the likelihood of aggression, a senior Russian official said on Wednesday.
While Russia amended its military doctrine years ago to allow for the possibility of using nuclear weapons first in retaliation to a non-nuclear attack, the statement by deputy prime minister Dmitry Rogozin reflected Moscow's concern about prospective US conventional weapons.
Weapons that have been developed in the United States under the so-called "prompt global strike" programme would be capable of striking targets anywhere in the world in as little as an hour with deadly precision. Russia, which has lagged far behind in developing such weapons, has described them as destabilising.
Without naming the US, Rogozin told lawmakers in comments carried by Russian news agencies said that those who "experiment with non-nuclear strategic weapons" should remember that "if we come under attack, we will undoubtedly use nuclear weapons in certain situations to defend our territory and state interests."
He said that it should discourage any potential aggressor.
"We have never underestimated the role of nuclear weapons as a 'great equalizer,'" Rogozin said.
The Russian doctrine mirrors the American strategy during the Cold War, when the US would not rule out using nuclear weapons first, because it feared it might have to do so in response to overwhelming conventional attack on western Europe by Soviet forces.
Rogozin said that Russia is working on developing its own version of the "prompt global strike" weapons, but wouldn't give any details.
The US plans included modifying some of the existing nuclear-armed missiles to carry conventional warheads as well as designing new vehicles capable of travelling at least five times the speed of sound.
Russian officials said that such US weapons wouldn't fall under any restrictions but would have combat efficiency comparable to nuclear weapons, and thus should be included in any prospective nuclear arms reduction talks.
Russian suspicions about the US intentions have aggravated tensions caused by a dispute over the US-led Nato missile defence programme, which Moscow sees as a threat to its nuclear deterrent.
Russia has increasingly relied on nuclear weapons in its military strategy to compensate for a post-Soviet decline in its conventional forces. The nation's military doctrine says it may use nuclear weapons to counter a nuclear attack on Russia or an ally, or a large-scale conventional attack that threatens Russia's existence.
Rogozin's comment comes a day after President Vladimir Putin pledged to continue an ambitious weapons modernisation programme and to expand Russia's military presence in the Arctic region.
Putin has pointed at the US navy presence in the Arctic Ocean as one of the reasons behind the buildup, saying that Russia is concerned because it takes US missiles just 15 to 16 minutes to reach Moscow from a submarine in the Barents Sea region.
The statements reflected the current strain in Russian-US relations, which have been hurt by disputes over the US-led missile shield, Russia's human rights record and, most recently, differences over Ukraine.