Russia could place missiles in neighbouring Belarus to counter a planned US missile defence system, a senior Russian general has said.
Russia has been upgrading its air defences lately
Col-Gen Vladimir Zaritsky spoke after Belarus, a close ally of Russia, said it would re-equip its forces with new Russian Iskander short-range missiles.
Russia says the US plan to site parts of a missile defence system in Poland and the Czech Republic is a threat.
The US says it is needed to counter missiles fired by states such as Iran.
"Any action must have a counter-action, including with the US anti-missile elements in the Czech Republic and Poland," Gen Zaritsky was quoted as saying by Russia's Itar-Tass news agency.
Gen Zaritsky is the commander of Russia's artillery and rocket forces.
'Battle of words'
The US missile shield system would see a radar site set up in the Czech Republic and a base in Poland for 10 missile interceptors.
The chief of staff of Russia's armed forces, Gen Yury Baluyevsky, said on Tuesday that Iran posed no missile threat to Europe or the US and that the missile defence plan would be aimed at Russia.
The US has said that the limited system it proposes could not threaten Russia's own missile arsenal.
Belarus says it will buy Russia's Iskander-E conventional missile system by 2020.
Gen Zaritsky's comments are a new stratagem in bitter battle of words between the US and Russia, says the BBC's James Rodgers in Moscow.
In October, US President George W Bush said: "The need for missile defence in Europe is real and I believe it's urgent."
He warned that Iran could have a ballistic missile capable of reaching Europe or the US by 2015.
A few days later, Russian President Vladimir Putin compared the US plans to the missile crisis of 1962, which saw the US and the Soviet Union go to the brink of nuclear war over Russian missiles in Cuba.
US MISSILE DEFENCE: LONG RANGE THREAT PROTECTION
US wants to build defence system against possible missile attacks
Part of defences would be in Eastern Europe - which Russia opposes
Russia suggests US should use its Gabala, Azerbaijan base instead