The United States and Russia began the hard bargaining today over a deal to slash their stockpiles of nuclear weapons.
An American negotiating team opened the first round of talks in Moscow with Russian officials about a replacement for the landmark 1991 Strategic Arms Reduction Treaty (START 1), which expires on December 5.
Both sides are under orders to produce results in time for President Obama's first official visit to Moscow in July. He and President Medvedev agreed to replace START with a new treaty when they met in London in April, and to work towards a long-term goal of "a nuclear free world".
The US experts are led by Assistant Secretary of State Rose Gottemoeller and the Russia team by Anatoly Antonov, the Foreign Ministry's head of security and arms control. The Foreign Ministry said that Russia was seeking "constructive dialogue and . . . practical results" from the two days of talks at a 19th Century mansion outside Moscow.
Relations between the US and Russia remain difficult, however, despite the Obama administration's efforts to "press the reset button" and the pressure on negotiators to reach a speedy deal.
The Kremlin wants the US to abandon plans for a missile-defence shield in Eastern Europe, which it says threatens Russia's security. It is likely to link agreement on arms reductions to a pledge to scrap the project, which the US insists is aimed at rogue states such as Iran.
President Obama has refused to ditch the shield so far. Instead, he has urged Russia to help make it unnecessary by working with the US to tackle Iran over its suspected nuclear weapons programme.
Tensions also continue over Russia's war with Georgia last August. The US accused Russia of breaching the peace agreement that ended the war after the Kremlin sent troops to take control of border security in Georgia's breakaway regions of South Ossetia and Abkhazia last month.
Russia announced that it would expand military exercises planned for next month across the North Caucasus region in response to Nato war games currently taking place in Georgia. It said that the large-scale exercises would be "comparable to those held during the Soviet Union".
The START treaty was signed by US President George H W Bush and Soviet leader Mikhail Gorbachev. They agreed to reduce nuclear stockpiles to no more than 6,000 warheads each, compared to a Cold War peak of 30,000.
That was followed by the 2002 Moscow Treaty, which limited both sides to a maximum of 2,200 warheads by 2012. Mr Obama and Mr Medvedev have set their negotiators the task of reducing strategic weaponry below this level.
The US currently has 2,200 strategic nuclear warheads deployed and Russia 2,800. Experts believe that they are willing to go down to 1,500 each, although The Times disclosed in February that Mr Obama was ready to seek even more radical cuts to 1,000 warheads each.
Mr Medvedev said during a recent visit to Finland that he wanted the new treaty to "limit the delivery systems of the nuclear warheads and not only the quantity of warheads themselves". He also demanded safeguards against a build up of conventional forces to compensate for a loss of nuclear weapons.
Mr Obama set out his vision of a nuclear-free world in a speech in Prague, Czech Republic, in April. He said that arms reductions should be accompanied by tougher rules to deal with countries that break the existing nuclear non-proliferation framework, such as Iran and North Korea.