In recent weeks, a succession of senior US officials traipsed to Moscow to begin consultations on deploying missile defences and cutting offensive weapons that Presidents George W. Bush and Vladimir Putin promised to intensify in Genoa last month. These early talks have illustrated the gulf that continues to separate the two sides.
The Bush administration wants Russia to agree to a mutual withdrawal from the 1972 anti-ballistic missile treaty. It is easy to see why. Co-operation from Moscow would, in effect, undermine opposition at home and abroad to Mr Bush's plans for deploying a limited missile-defence system.
So far, however, Russia has shown little interest in withdrawing. While it has signalled the possibility of amending the treaty, it insists that the treaty remains the cornerstone of strategic stability.
Time is running out. The Bush administration has told Congress and its allies that in order to proceed with robust missile-testing, the US must withdraw from the ABM treaty within "months, not years". By next spring it wants to begin building a new test facility in Alaska. And it wants to conduct tests of sea-based and mobile land-based radar that the treaty currently prohibits.
The US and Russia will avoid a collision only if they show greater flexibility. The key is to separate the issue of Washington's immediate testing programme from a final resolution of differences over future defensive deployments.
Solving the testing issue should be straightforward. The ABM treaty permits the construction of additional test ranges by mutual agreement, provided these facilities do not constitute a basis for deploying a nationwide defence. Moscow should agree to the new Alaska site, while Washington should limit the number of missile launchers and interceptors at the site to make clear its purpose is for testing only. Moscow could also allow the US to conduct a limited number of tests using mobile and ship-based radar. In return, Washington would promise not to walk away from the treaty for now.
Such a deal would buy time to devise a settlement on the broader issue of what kinds of offensive and defensive capabilities the two countries could deploy. The Bush administration has yet to decide what sort of defence it wants or how deeply to cut the US long-range nuclear arsenal. Serious negotiations are impossible until it makes up its mind.
Even without these details, however, it is possible to sketch out the basic contours of a deal that could satisfy much of what both countries want. It would allow deployment of the limited missile defence that Washington seeks and give Moscow the much lower nuclear arsenals it wants. Such a deal would have four basic components.
First, deep cuts in offensive nuclear forces need to be negotiated. A decade after the Soviet Union disintegrated, it is absurd that the US and Russia have nuclear arsenals larger than at any time in the first four decades of the cold war. Both sides should, therefore, immediately agree to reduce each arsenal to 1,500 weapons.
Second, restrictions on testing and development of missile defences should be lifted. The provisions of the ABM treaty limiting testing and development of defensive technologies have been overtaken by events. Both countries should be allowed to investigate which technologies are most likely to work effectively in dealing with new missile threats.
Third, deployment of a limited missile defence system should be allowed. The ABM treaty sought to ban strategically significant defences - those that could pose a threat to the other side's nuclear deterrent. That ban must remain in place. But each side should be allowed to deploy defences capable of providing some protection against rogue states. An agreement that allows the deployment of boost-phase defences capable of shooting down enemy missiles shortly after launch but that also strictly limits the number of mid-course interceptors and bans all space-based weaponry would strike the right balance.
Last, each side should agree to a 10-year review. This is necessary to allow the US and Russia to propose modifications as circumstances change.
Russia's recent public comments suggest that it could live with such an arrangement, particularly if the alternative were no treaty at all. Mr Bush's comments have been less reassuring. Last week he affirmed that he planned to "withdraw from the ABM treaty on our timetable, at a time convenient to America".
Nevertheless, there are powerful political incentives for the White House to seek an agreement with Russia. Mr Bush would calm the growing impression in Europe that he is an unabashed unilateralist. Meanwhile, Democrats at home could hardly object to a defence system that Moscow can live with.
Standing up to the Republican zealots bent on destroying all arms-control treaties in their pursuit of the chimera of invulnerability is a small price for such rewards.