US President Barack Obama has written his Russian counterpart about links between controversial US plans to deploy a missile defense system in Europe and the Iranian "threat," a senior US official said on Tuesday.
The official was responding to a report published on Tuesday in The New York Times that Obama, in a secret letter to Russian President Dmitry Medvedev, offered to halt deployment of the missile defense shield if Iran end any efforts to build nuclear weapons to ballistic missiles.
"President Obama sent a letter to Medvedev covering a broad range of topics, including missile defense and how it relates to the Iranian threat," the White House official told AFP on condition of anonymity.
The official offered no further details of the letter, or when it was sent.
But the Times said the letter was delivered to Moscow by "top administration officials" three weeks ago.
Moscow has been angry for years over former president George W Bush's plans to place missile defense sites in Poland and the Czech Republic, saying the move was directly aimed against Russia.
Bush officials said it was intended to counter missile threats from states such as Iran, which Washington accuses of trying to develop nuclear weapons.
Iran has rejected repeated calls by the UN Security Council, of which Russia is a permanent member, for a halt to uranium enrichment, despite three sets of sanctions being imposed for its defiance.
While the officials cited by The New York Times said Obama's letter did not make a direct link between halting the missile defense effort and Russia helping pressure Iran to drop its nuclear ambitions, "the letter was intended to give Moscow an incentive to join the United States in a common front against Iran."
"It's almost saying to them, put up or shut up," a senior official was quoted as saying.
"It's not that the Russians get to say, 'We'll try and therefore you have to suspend.' It says the threat has to go away."
Moscow has not responded, but the issue was expected to come up when US Secretary of State Hillary Clinton meets Russian Foreign Minister Sergey Lavrov Friday in Geneva.
On Sunday, Medvedev was quoted in Moscow as saying that Russia was awaiting new US proposals to resolve the missile defense dispute.