Russian President Vladimir Putin has said his country would add more than 40 new intercontinental ballistic missiles to its nuclear arsenal this year.

Putin's comment came at the opening of an arms show near Moscow on Tuesday, a day after Russian officials denounced a US plan to station tanks and heavy weapons in NATO states on Russia's border as the most aggressive US act since the Cold War.

"More than 40 new intercontinental ballistic missiles able to overcome even the most technically advanced anti-missile defence systems will be added to the make-up of the nuclear arsenal this year," Putin said.

Putin also noted that the military was to start testing its new long-range early warning radar intended to monitor the western direction.

Russia-West relations have plunged to their lowest point since the Cold War over Moscow's annexation of Ukraine's Crimea Peninsula and support for the pro-Russia separatists in eastern Ukraine.

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The US and the EU have slapped Russia with economic sanctions, and Washington and its NATO allies have pondered an array of measures in response to Russia's moves.

Russia's Nuclear Arsenal Russia has a military stockpile of about 4,500 warheads - only 200 short of the US. Almost 1,800 of the Russian warheads are deployed strategically across the world to bases and on missiles. Putin says the 40 new intercontinental ballistic missiles will help the Russian economy. Experts warn the total cost of the re-armament programme will be more than $400bn and would be a huge burden on the economy.

NATO Secretary-General Jens Stoltenberg condemned Putin's announcement.

"This nuclear sabre rattling of Russia is unjustified, it's destabilising and it's dangerous," he said.

The three Baltic members of the alliance, Estonia, Latvia and Lithuania, have asked NATO to permanently deploy ground troops to their nations as a deterrent against an increasingly assertive Russia. And Polish Defence Minister Tomasz Siemoniak said on Sunday that he and US Defence Secretary Ash Carter held talks about placing heavy US army equipment in Poland.

Moscow bristled at the plans, warning Washington that the deployment of new US weapons near Russian borders would foment dangerous instability in Europe.

"The United States is inciting tensions and carefully nurturing their European allies' anti-Russian phobias in order to use the current difficult situation for further expanding its military presence and influence in Europe," the Russian foreign ministry said.

"We hope that reason will prevail and it will be possible to save the situation in Europe from sliding towards a military standoff which could entail dangerous consequences," it added.