Following last weekend's summit with President Clinton, Russian President Vladimir Putin proposed that NATO and Europe jointly develop a missile defense as an alternative to a unilateral plan proposed by the U.S.
Washington says it needs a shield against possible attacks by hostile nations such as Iran and North Korea, which is projected to have long-range missile capability by 2005.
Cohen told reporters on a plane en route to Brussels, "It could be a constructive proposal but it could be simply a tactic to divide the European members of NATO from the United States.
"We've got to look at exactly what he has proposed in great detail before even making any realistic assessment of what he has in mind."
But he said Putin's acknowledgement that a threat existed was a significant shift and hoped that could lead to working together to address it.
"Just a few weeks ago their official position was that there was no threat, that it was largely being exaggerated," Cohen said.
Russia's Interfax news agency reported Wednesday that Defense Minister Igor Sergeyev would present a plan for joint anti-ballistic missile defense when he meets NATO defense chiefs in Brussels this week.
The agency quoted unnamed sources as saying Sergeyev would "give an explanation and put forward concrete proposals on this question, expanding on the initiative earlier proposed by President Vladimir Putin."
Meanwhile, in Hong Kong, U.S. Assistant Secretary of State Robert Einhorn on Wednesday dismissed a warning by China that a U.S. anti-missile defense system would fuel a new arms race.
"We see no reason why the Chinese need to build up their capability beyond the level that they are already building up that capability. We see certain modernization efforts by China now," he said. "It's not clear that a limited defense and deployment would require any change in China's existing modernization plan."
Einhorn said Washington had spoken to Beijing about the plan for an anti-missile defense system and would assure China that it would be in no way threatened by the defense system.
European allies also have expressed concerns that the U.S. plan for a missile defense may lead to a renewed arms race. But Cohen said many allies would be more comfortable if it were done in the context of modifying the 1972 Antiballistic Missile Treaty (ABM), an arms control pact with Russia.
"In all of my dealings with the Russians they have adamantly opposed any consideration of changing ABM because there was no threat. So now they've said there is a threat, let's see if we can't work cooperatively together to deal with the threat in a way that doesn't pose a threat to them," ohen said.
The U.S. has been trying to gather support from European allies for its national missile defense (NMD) proposal.
"Many changed their mind, many understood the nature of the threat and were reasonably comfortable with the way in which we were approaching it, mainly in the context of a modified ABM," he said. "I think once you get beyond that then there's some pretty strong opposition within NATO itself."
Cohen said the focus now was whether the ABM Treaty could be modified to allow the missile defense program to move forward. Clinton was expected to make a decision later this year on whether to go ahead with the system.
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