Nuclear Pact’s Chances Put at Better Than 50-50 : Negotiations: Eagleburger arrives in Geneva for talks. He is upbeat on likelihood of U.S., Russia signing treaty to cut arsenals.

Secretary of State Lawrence S. Eagleburger, arriving for make-or-break arms control talks, said Sunday that there is “a better than 50-50 chance” that the United States and Russia will sign a treaty cutting nuclear arsenals by more than two-thirds before President Bush leaves office.

Eagleburger negotiates today with Russian Foreign Minister Andrei A. Kozyrev and Defense Minister Pavel S. Grachev in an effort to settle three complex disputes that have confounded arms experts ever since Bush and Russian President Boris N. Yeltsin signed a “framework agreement” in Washington last June.

Talking to reporters aboard his U.S. Air Force jetliner on the way to Geneva, Eagleburger said Washington is ready to accept a compromise that would allow Russia to keep some of the silos protecting its giant SS-18 missiles and permit Moscow to convert some of its six-warhead mobile SS-19 rockets to the single-warhead weapons that it would be allowed to retain under the proposed treaty.

But he said there is no agreement yet on how many of Russia’s top-of-the-line weapons would survive the destruction required to cut U.S. and Russian arsenals from more than 10,000 warheads apiece today to between 3,000 and 3,500 each by the year 2003.

Although Eagleburger said he is willing to continue the talks Tuesday if no agreement is reached today, he said he believes that the remaining disputes can be settled in one day if they are to be settled at all.

At the same time, he said this meeting is almost surely the last attempt to complete the pact before Jan. 20 when President-elect Bill Clinton replaces Bush in the White House.

“If we can’t settle it this time, I think it’s going to be very difficult to get it settled before the end of this Administration,” Eagleburger said.

Clinton has not taken a firm public position on the pending pact, known as START II for the second Strategic Arms Reduction Treaty. But even if he embraces the Bush-Yeltsin framework and accepts the detailed bargaining that has taken place since, it would take months for the new State Department to get ready to complete the negotiations. And, by that time, Yeltsin’s embattled government may no longer be willing to accept a treaty that hard-line Russian nationalists claim is unfairly balanced in Washington’s favor.

If Bush and Yeltsin sign the treaty before Bush leaves office--and if the Senate and the Russian Parliament ratify it--the pact will be binding on both nations despite the change of administrations in Washington. If not, U.S. and Russian negotiators may have to start over from scratch, possibly losing out on what shapes up as the most ambitious arms control agreement in history.

“If you’d asked me a month ago, I would have thought we were unlikely to succeed,” Eagleburger said. But he said that talks since, including two telephone conversations between Bush and Yeltsin and a three-day meeting of experts last week, have produced substantial progress.

“There is a . . . better than 50-50 chance we can get an agreement,” Eagleburger said. “I don’t know how much better.”

Even if Eagleburger’s talks with Kozyrev and Grachev settle the remaining policy issues, the secretary of state said it will take at least 72 hours for U.S. and Russian experts to complete the formal drafting of the pact and make sure that the English and Russian texts say the same thing.

For the past several weeks, negotiators have been hung up on three complex issues: destruction of Russia’s SS-18 silos, conversion of the six-warhead Russian SS-19s to a single warhead and a complex formula for determining the number of nuclear bombs carried by U.S. B-1 and B-52 bombers.

At the heart of all three controversies are the budget crunches in both Washington and Moscow. Both sides want to take steps that are prohibited under decades of Cold War-era arms control rules to save money. With the reduction in tensions that came with the end of the Cold War, both countries insist that the rules can be bent a bit. But both also want to make sure the START II treaty can be verified and enforced.

Under the still-unratified START I agreement signed by Bush and former Soviet President Mikhail S. Gorbachev, Moscow is required to destroy half of its stock of 308 10-warhead SS-18 missiles, the most powerful nuclear-weaponry rocket in the world. The START II pact would require Russia to get rid of the other half. Under START I, the silos must be destroyed to prevent cheating. However, the Russians now want to keep some of the remaining 154 silos and convert them to other uses as an economy measure.

Similarly, Russia and the United States have already agreed that START II will ban all land-based intercontinental ballistic missiles with more than one warhead. Moscow wants to convert the SS-19s to single-warhead missiles to avoid the cost of developing a new one-warhead rocket. But under earlier arms control rules, a weapon is assumed to carry the maximum number of warheads for which it was designed, a regulation that would require destruction of all SS-19s.

Washington wants to convert some of its bombers from nuclear to conventional missions, in part to avoid the cost of buying new conventional bombers

Eagleburger said Sunday that Washington is ready to compromise on the SS-18 and SS-19 issues. But he said the bomber dispute may prove to be the most difficult to settle.