The United States will go ahead with deployment of a test version of its missile shield without waiting for Moscow's agreement, US National Security Adviser Ms Condoleezza Rice announced yesterday after meeting the Russian President, Mr Vladimir Putin.
Ms Rice, in Moscow for talks on missile defence, said there was no question of Washington waiting for Russian acceptance before going ahead with the programme. Russia has said that such a programme would breach the 1972 Anti-Ballistic Missile Treaty and it has warned that this may trigger a new arms race.
The move, which is likely to up the ante between the world's main two nuclear powers, comes after a week of confusing diplomacy between Moscow and Washington. After meeting at the G8 summit in Genoa last weekend, President Bush and President Putin announced they had come to a compromise which would end the deadlock between the two.
The new move would see the US's desire for a missile shield linked to Russia's desire for further steep reductions in the two sides' strategic nuclear arsenals.
But on Monday both sides backtracked, with Mr Putin announcing that while productive, the talks had seen "no breakthrough" and reiterating that whatever the result, he remained opposed to missile defence. Mr Bush countered that he would not wait indefinitely for Russia's agreement.
Now it appears to have gone a stage further, with the US saying, in effect, that while talks to get Russian agreement will continue, so will deployment of the missile system, in test form.
Ms Rice was dispatched to Moscow to get this talks progress going, and she emerged in bouyant mood, saying that discussions would now get under way, with the US keen to listen to Russian objections to the system.
Groups of experts will begin meetings shortly, followed by ministerial contacts and finally a meeting between Presidents Bush and Putin in Shanghai, China, in October. It is likely the two sides will remain deadlocked by then.
The US, already setting up components of its testing programme for the proposed missile shield, says time is of the essence. But Russian security adviser Mr Vladimir Rushailo said the issue might take far longer - in particular because even if Russia accepts a limited system, there must be changes to the 1972 treaty.
Diplomats in Moscow say the US officials are working hard to point out that their missile system is anyway limited to hitting individual missiles fired by so-called "rogue states", including North Korea, Iran and Iraq.
Russian officials counter that in the short term this will encourage the "rogues" to expand their missile programmes, and in the long term even a limited system can be expanded to provide a complete shield against Russia's missiles, upsetting the strategic balance.