ALTHOUGH there are still major differences to overcome, the United States and Russia are close to agreeing on yet more deep cuts in long-range nuclear weapons - reducing stockpiles to levels that, a few years ago, most military analysts would have thought unbelievably low.
It is an indication of today's world political context that this new agreement may come to fruition even though last year's signed-and-sealed arms deal, the START pact, has not been implemented or even ratified by the US Senate.
Final details have a way of stalling arms talks for weeks or even months at the last moment. But if Presidents George Bush and Boris Yeltsin do sign a nuclear deal next week, strategic warheads will likely be limited to 4,700 apiece. That's down from the 11,000 to 12,000 long-range nuclear weapons both sides had on the eve of the START signing last July.
"There's a genuine recognition on the part of both countries that we ought to reduce the levels of these weapons in light of the new political environment as substantially and as quickly as possible," said Secretary of State James Baker III after meeting with Russian Foreign Minister Andrei Kozyrev earlier this week.
Both sides want a START 2 agreement to be ready in time for the Washington summit meeting between Mr. Bush and Mr. Yeltsin June 16-17. But no further negotiation sessions are scheduled before then, and Mr. Baker is scheduled to travel with Bush to the Rio environment meetings over the weekend.
"I don't expect anything till after the Rio meeting, if then," says a US official.
The foundation for the START 2 pact was laid early this year, when Yeltsin proposed cutting strategic weapons to around 2,500 and Bush countered in his State of the Union address with an offer which worked out to around 4,500.
Through late winter and early spring, however, the administration's highest policy priority was simply keeping together the START 1 agreement, which had been signed last July by Bush and then-Soviet President Mikhail Gorbachev. This involved urging the ex-Soviet republics with nuclear weapons to agree to START terms and turn their weapons over to Moscow.
After START 1 was finally nailed down in late May, attention returned to follow-on cuts. The Russians now have accepted the American proposal to limit strategic warhead arsenals to 4,700. But there is still disagreement about the types of weapons that will be allowed under this numerical cap.
"It's not enough to simply say reduce weapons.... You have to consider reductions of those weapons that are of the most destabilizing nature," said Secretary Baker.
Specifically, this means the US wants to ban all land-based, multiple-warhead ballistic missiles. This is an area in which Russia is widely considered to have a military advantage, with its big SS-18, 10-warhead ICBMs long being the weapon Pentagon planners have been most concerned about. In return, the US has offered to make some cuts in the strategic area where it holds the advantage: submarine-carried ballistic missiles.
But the US submarine force would remain largely intact, and Yeltsin complained Wednesday that this mix would give the US a military advantage. According to the US, Russian negotiators have offered to limit land-based multi-warhead missile weapons to around 30 percent of their total, or about 1,410.
Under the US proposal, Russia would have to scrap all its modern SS-18 and SS-24 ICBMs. With retirement of older missiles continuing, it is likely Russia would have to actually build and field new weapons to deploy 4,700 warheads.
"This is economically impossible," says Jack Mendelsohn, deputy director of the nongovernmental Arms Control Association.
By the strict rules of nuclear theory there is some value in getting rid of land-based multi-warhead missiles. Weapons that are both fearsome and easy to locate, they might tempt an adversary to try to knock them out with a preemptive punch in a crisis.
But any leader willing to take that awful gamble would be ignoring the retaliatory power of largely invulnerable sea-based weapons. And in today's warmer political atmosphere, such calculations are irrelevant anyway, argues Mr. Mendelsohn.
"We ought not to get stuck over a very narrow issue of force structure," he says.
There is also the question of nuclear command and control. Considering the volatile current nature of Russian politics, the US might want to encourage the Russian military to keep close watch on its nuclear trigger.
Land-based missiles, with buried control cables and radio, are the easiest weapons to keep an eye on. Submarines, with chancy communications at sea, are the hardest.
"Do we really want them to push more of their nuclear force structure into subs?" asks Greg Weaver, a senior military analyst for the SAIC Corporation, a consulting firm.
With the US and Russia moving toward a relationship more like that of allies than adversaries, nuclear exchange calculations are beginning to seem a little outdated. Instead, military cooperation may be the wave of the future.
Baker noted earlier this week that he and his Russian counterpart found "substantial common ground" in discussing creation of a joint early-warning system which would share information in case either side were attacked by a missile launched from any location.