President Obama sent a secret letter to his Russian counterpart last month suggesting that he could halt the deployment of a US missile shield in Eastern Europe if Moscow persuaded Iran to abandon its nuclear weapon ambitions, it emerged yesterday.

The overture to President Medvedev is part of a diplomatic effort by the Obama Administration to improve American-Russian relations on a range of issues including Iran, Afghanistan and the reduction of nuclear stockpiles.

Part of Mr Obama’s diplomatic initiative on cutting nuclear weapons, which was first reported by The Times last month, involves the possibility of shelving the $4 billion a year (£2.8 billion) missile defence programme as an incentive for Moscow to negotiate a new arms reduction treaty with Washington. Mr Obama also views Russia as critical in his efforts to halt Iran’s suspected nuclear weapons programme and confront the resurgent Taleban in Afghanistan. His diplomatic push appeared to have paid early dividends when it emerged that the first delivery of non-military supplies for US troops in Afghanistan had crossed Russian territory.

The planned deployment of ten interceptor missiles in Poland and a radar in the Czech Republic — a programme begun under the Bush Administration — has been opposed by Moscow because the Kremlin claims that it would threaten Russian security. It is emerging as a useful bargaining chip for Mr Obama as he seeks to co-opt Moscow’s help on a number of global challenges.

Asked about the letter during a press appearance with Gordon Brown at the White House, Mr Obama said that it contained no quid pro quo linking the missile defence shield to Russian help in halting Iran’s nuclear programme. “What I said in the letter was that obviously to the extent that we are lessening Iran’s commitment to nuclear weapons, then that reduces the pressure for, or the need for, a missile defence system.” He added: “The missile defence that we have talked about deploying is directed towards not Russia, but Iran.”

Mr Obama added: “We’ve had a good exchange between ourselves and the Russians. I’ve said that we need to reset or reboot the relationship there.

“My hope is that we can have a constructive relationship where, based on common respect and mutual interest, we can move forward.” Russia has significant influence in Iran. It is close to completing construction of Iran’s first atomic reactor and signed a contract last week to deliver civilian nuclear fuel for the next ten years.

Mr Medvedev confirmed that he had received Mr Obama’s letter, although he insisted that on the issue of Iran, there was “no talk about some kind of trade-off or quid pro quo”. He said that it was “not productive” to link talks over the missile defence shield to Iran’s suspected nuclear weapons programme.

Mr Medvedev said that he was encouraged by the approach from Washington after President Bush’s hardline stance on the missile defence shield.

Speaking in Madrid during a press conference with José Luis Rodríguez Zapatero, the Spanish Prime Minister, Mr Medvedev said: “It’s good because several months ago we were getting different signals: that the decision [on the missile shield] has been made, there is nothing to speak about, that we have done everything as we have decided.” He added: “Our American partners are ready to discuss this problem. This is already good.” He said that Russia was working very closely with the US over Iran’s nuclear programme.

Hillary Clinton, the US Secretary of State, said that she would discuss the issue of the missile shield at length with Sergei Lavrov, the Russian Foreign Minister, on Friday in Geneva.

Asked about the issue in Jerusalem, she said that the missile defence system “has always been to deter any missile that might come from Iran. We have explained that to the Russians before.”

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