The US Administration is expected today to formally notify Russia of its intention to withdraw from the 1972 Anti-Ballistic Missile treaty (ABM) in order to pursue testing for its controversial missile defence programme.
President Bush has repeatedly said he regards the treaty as a relic of the Cold War unsuited to the challenges of the 21st Century.
Mr Bush yesterday told the Senate Majority leader, Mr Tom Daschle, and congressional leaders he was about to invoke the six-month withdrawal clause, in effect acknowledging the failure of attempts to persuade the Russians to amend the treaty.
The decision was taken following the visit in recent days of the Secretary of State, Mr Colin Powell, to Moscow and represents a setback to his desire to proceed by negotiation.
The repudiation of the treaty represents a victory for the Secretary of Defence, Mr Donald Rumsfeld, who has argued the treaty could never be amended sufficiently to meet US requirements. He was supported by the National Security Adviser, Dr Condoleezza Rice.
The decision is likely to embarrass European allies and the Russians who see the move as destabilising of the nuclear balance. But US officials believe the Bush-Putin relationship is robust enough to survive a decision that Moscow clearly expected.
The treaty is a cornerstone of classical deterence-based nuclear defence. By prohibiting the two signatories, Russia and the US, from building effective defensive systems each side was constrained from an attack on the other by the certainty that retaliation would get through to its major population centres. Mr Bush argues that such a rationale is no longer appropriate in an age where rogue states like Iraq, Iran, or North Korea, may be tempted into a strike against the US in a desperate, irrational final throw of the dice.
Only a missile defence shield, although technically unproven, he says, can provide the security the US needs.
Yet while the Russians, still equipped with a formidable armoury that could easily overwhelm anything the US is likely to create, may view the move as regrettable but inevitable, there are fears that it may ignite a new arms race in Asia where, China, India and Pakistan may feel they must respond by building their missile forces up to a point where they could once again pose a threat.
A clause in the treaty provides that either party can repudiate it "if it decides extraordinary events relating to the subject matter of the treaty have jeopardised its supreme interests".
The move is also likely to provoke anger from Democrats. "Unilaterally abandoning the ABM treaty would be a serious mistake," Senator Joseph Biden, the Democrat chairman of the Senate Foreign Relations Committee, said. "The administration has not offered any convincing rationale for why any missile defence test it may need to conduct would require walking away from a treaty that has helped keep the peace for the last 30 years."
Meanwhile, the House was voting last night on a $2.6 billion package to improve states' voting systems. Legislators anxious to avoid a repeat of last year's Florida presidential fiasco have after lengthy negotiations agreed minimum standards but gives states leeway to craft their own improvements.
About 36 per cent of US voters used a punch card machine last year, federal officials say.
Russia is aware the US may soon unveil plans to withdraw from the ABM treaty and is monitoring the situation carefully, Interfax news agency has said. Interfax quoted a senior Foreign Ministry official as saying the Russian leadership was "not dramatising this situation and will keep an attentive eye on the development of events".
