Yeltsin’s Joint Missile Net Worth Exploring, Bush Says : Arms control: But senior U.S. officials are believed to have serious reservations about the Russian leader’s proposal.

President Bush, without committing himself to embrace the idea, said Saturday that Russian President Boris N. Yeltsin’s proposal for cooperation on a global missile defense system is “worth discussing in much more detail” in coming weeks.

Bush, who had previously avoided direct comment on the proposal, even hinted that studying the idea might be a way to employ ex-Soviet nuclear scientists at home so they would not be tempted to sell their know-how to Third World nations seeking atomic bombs.

“We’re prepared to discuss President Yeltsin’s idea that he announced the other day in full detail. It has a lot of interest for us,” Bush told reporters.

“Perhaps one area of real cooperation can be in future space adventures,” Bush said after his Camp David meeting with the Russian leader.

“Another could be in this area of defense, but we reached no conclusion, except to say that we felt it was worth discussing in much more detail.”

Despite the receptive tenor of Bush’s words, senior Administration officials involved with national security policy are believed to have serious reservations about any such joint undertaking--in part because U.S. research and development on antimissile defenses is far more advanced than Russia’s.

Also, both the cost and technical problems associated with a global system would be immense.

In expressing interest in the idea, Bush, whose overriding goal at Camp David was to demonstrate Washington’s support for the Russian leader as he struggles against daunting economic and political problems, may have been motivated primarily by a desire to avoid striking a negative note by rejecting Yeltsin’s proposal.

Nonetheless, by pressing the plan at every turn in recent days, Yeltsin has brought back into the public spotlight an idea that was first promulgated by President Ronald Reagan.

Yeltsin has made the proposal the centerpiece of his sweeping proposals for cooperation on arms control, arguing that a global antimissile shield would give all nuclear powers and would-be nuclear powers sufficient security to eliminate such weapons.

A White House official said arms issues were discussed between the two presidents “not in the context of cooperating on mutual defenses but only as an investment in security to prevent a brain drain of scientists from Russia.”

“They didn’t discuss arms as such,” the senior official added, referring to the U.S. and Russian proposals to cut offensive nuclear weapons. “And they didn’t discuss ‘Star Wars’ (the U.S. missile defense program) in terms of what the United States has in mind.

“So we’re really left scratching our heads about what Yeltsin meant,” the official said, when he called for a “global” missile defense system, developed and built “jointly” by the United States and the nations of the former Soviet Union.

That issue and others will be discussed further when Secretary of State James A. Baker III visits Moscow in about two weeks. But the Administration is unlikely to embrace Yeltsin’s offer, despite Bush’s careful words on the subject, for several reasons.

Politically, the offer is seen by many U.S. analysts as essentially an “all-or-nothing” idea: all, in that the joint system Yeltsin wants would be built mostly with U.S. technology and money; or nothing, in that Yeltsin could otherwise demand strict adherence to “all provisions” of the 1972 Anti-Ballistic Missile Treaty.

The treaty, as it stands, rules out such a system.

The Administration is seeking to renegotiate the ABM treaty to permit its so-called G-PALS system to be built.

G-PALS, for Global Protection Against Limited Attack, would build 1,000 interceptors on the ground and put 1,000 in space orbit to protect against unauthorized or accidental launches. Cost is estimated at $61 billion.

Policy questions aside, the American public and Congress would probably balk at a joint program, particularly in the current economic situation. Russia, for its part, is too broke to afford anything like half the program cost.

“It may be appealing, but it isn’t at all practical,” said Jack Mendelsohn, deputy director of the private Arms Control Assn. RAND Corp. analyst Edward L. Warner III agreed.

Meshing U.S. and Russian technology would also be very difficult and make the program still more costly.

Yeltsin’s proposal is also seen to challenge Washington’s claim that the purpose of the Strategic Defense Initiative, or “Star Wars” as the antimissile program is sometimes known, is to stabilize the nuclear balance, whether it is a nationwide umbrella like that envisaged by Reagan or the more modest G-PALS proposed by Bush.

If Washington really wants stability, Yeltsin argued, it should make any defense network universal, so that no nation gains an advantage.

When Baker goes to Moscow, he is expected to also deal with two other arms issues Yeltsin raised in the past week: the targeting of nuclear missiles and cutting deeper into offensive nuclear arsenals.

On further weapon cuts, Bush proposed reductions to about half the 6,000-warhead ceilings provided in the Strategic Arms Reduction Treaty (START), and Yeltsin followed with an offer to go down to between 2,000 and 2,500 warheads. The upcoming Moscow meetings will seek to bridge the difference of about 1,000 weapons.

These figures refer to what are called “accountable” weapons under the complex counting rules contained in the START treaty. Essentially, each ballistic missile warhead counts as one; but bombers and bomber-carried weapons count as less than one.

A bomber carrying 20 cruise missile counts as only 10 warheads, for example.

The effect is that 6,000 “accountable” warheads could mean 9,000 actual nuclear weapons of various kinds, depending on how bombers are loaded, and the 3,000 to 3,600 “accountable” warheads in the latest Bush offer could mean about 4,600 actual U.S. weapons.

Yeltsin did not disclose how many actual warheads would be permitted under his proposal for 2,000 to 2,500 “accountable” weapons.