President Vladimir Putin says Russia
will update its nuclear arsenal with more than 40 intercontinental
ballistic missiles in 2015.
Speaking at an arms fair, Mr Putin
said the weapons would be able to overcome even the most technically
advanced anti-missile defence systems.It comes after the US proposed increasing its military presence in Nato states in Eastern Europe.
Tensions are high over Russia's role in the conflict in eastern Ukraine.
Nato and Western leaders accuse Russia of sending soldiers and heavy weapons, including tanks and missiles, to the pro-Russian separatists in eastern Ukraine. Russia has repeatedly denied this, insisting that any Russians fighting there are "volunteers".
'Arms race'
The 40 nuclear missiles that Mr Putin referred to on Tuesday are not additional missiles, but replacements for old ones, says the BBC's Sarah Rainsford in Moscow.The new ones are more high-tech and capable of penetrating anti-missiles defences, our correspondent adds.
Russian officials have warned that Moscow will respond if the US carries out its plan to store heavy military equipment in Eastern Europe, including in the Baltic states that were once part of the Soviet Union.
"The feeling is that our colleagues from Nato countries are pushing us into an arms race," RIA news agency quoted Russian Deputy Defence Minister Anatoly Antonov as saying on the sidelines of the arms fair outside Moscow.
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