President Vladimir Putin says a comment made by US presidential candidate Mitt Romney has made Russia feel justified in opposing America's missile defence plans in Europe.

The Republican challenger to President Barack Obama has branded Russia the "No 1 geopolitical foe" of the United States.

Putin said that statement shows Russia is right to criticise the US-led Nato plan to place land- and sea-based radars and interceptors in several European locations.

ANDRES STAPFF/ Reuters 'PROVED RIGHT': Russian president Vladimir Putin.

Washington says the shield is intended against a possible missile attack from Iran, but Moscow sees it as a threat to its security, saying it may eventually grow powerful enough to undermine Russia's nuclear deterrent.

Putin said in remarks carried by Russian news wires that Romney's statement has "strengthened Russia's positions in talks on this important and sensitive subject", but added that he would work with Romney if he wins the election.

"I'm grateful to him for formulating his stance so clearly, because he has once again proven the correctness of our approach to missile defence problems," Putin said of Romney.

"The most important thing for us is that even if he doesn't win now, he or a person with similar views may come to power in four years. We must take that into consideration while dealing with security issues for a long perspective."

Nato has offered to co-operate with Russia on the missile shield, but the alliance has rejected Russia's proposal to run the shield jointly.

Without a Nato-Russia cooperation deal, the Kremlin has sought guarantees from the US that any future shield is not aimed at Russia and threatened to aim missiles at the US shield if no agreement is reached.