The United States yesterday signalled a willingness to slow down plans for a missile defence shield in eastern Europe if Russia agreed to help stop Iran's nuclear weapons programmes.
"If we are able to work together to dissuade Iran from pursuing a nuclear weapons capability, we would be able to moderate the pace of development of missile defences in Europe," a senior US administration official said.
He spoke as Undersecretary of State William Burns held talks in Moscow, the most senior US official to do so since US President Barack Obama took office last month.
Mr Burns signalled the United States was ready to look at remodelling its missile defence plans to include Moscow.
"(Washington is) open to the possibility of cooperation, both with Russia and Nato partners, in relation to a new configuration for missile defence which would use the resources that each of us have," Interfax news agency quoted him as saying. Mr Burns gave no details.
In another sign that strained relations may be thawing, European Union foreign policy chief Javier Solana said US Secretary of State Hillary Clinton would meet Russia's Foreign Minister in Geneva next month.
The more flexible US position on its missile shield addressed one of Russia's chief complaints against Washington. Moscow viewed the plan to site missiles in Poland and a radar tracking station in the Czech Republic as a threat to its security in its traditional backyard.
The Kremlin has been pressing Washington to give ground on the proposed missile shield in exchange for Russia helping supply the US-led military campaign in Afghanistan.
But the US official in Washington focused on Iran.
"The impetus for the deployment of the missile defence systems is the threat from Iran. If it is possible to address that, then that needs to be taken into consideration as you look at the deployment of the system," the US official said on condition of anonymity.
The United States has led a drive to isolate Iran over its nuclear programme, which the West fears is a cover to develop atomic weapons and Tehran insists is for the peaceful generation of electricity.
Mr Obama has said he is prepared to talk to Iran's leaders and offered economic incentives if Tehran "unclenches its fist".
The administration official said Mr Burns' comments were "more expansive" than what had been said in the past. Former President George W. Bush, pushed the Russians to cooperate in the project without success.
US Vice President Joe Biden told a security conference in Munich, Germany, last week that the United States would press ahead with the missile defence shield if it was proven to work and was cost-effective.
But he also said Washington wanted a new relationship with Moscow and planned to hit the "reset button" in its relations with the former Cold War foe.
Ties were badly strained last year by the Russian invasion of Georgia, the missile shield and the US diplomatic recognition of the new independent state of Kosovo, which Moscow opposed.
The administration official said the United States wanted to pursue a "cooperative arrangement" with Moscow and that Mr Burns's trip to Moscow was a "signal of our seriousness of wanting to engage".
Russia's ambassador to Nato, Dmitry Rogozin, said Moscow would have to wait to see how Washington follows up on Mr Burns' remarks.
The Bush administration pushed ahead with plans to deploy interceptor missiles in Poland and a radar in the Czech Republic to counter possible missile strikes from what it called "rogue states", specifically Iran.
Moscow says Tehran does not have the capability of hitting Europe and sees the shield as designed to neutralize Russia's nuclear arsenal. It has threatened to deploy missiles on Poland's border if the shield goes ahead.