Russian President Vladimir Putin announced after talks with North Korean leader Kim Jong-Il on July 19 that Pyongyang would shut down its missile program should other nations provide it with rocket boosters for space exploration.

"It's unclear to me exactly what the offer is," Cohen told reporters. "It is still fairly ambiguous ... and it would require a great deal more clarification before I could comment that it was a positive proposal or not."

Cohen noted that during a recent visit to Kuala Lumpur, the top North Korean negotiator "also made the statement that (the North Korean) missile policy is to develop, to produce, and deploy powerful missiles continuously."

"So we have to weigh one statement against the other and get clarification before any judgment could be made about the validity and indeed the advisability of the (North Korean) proposal," he said.

Over the weekend at the Group of Eight summit in Japan, US President Bill Clinton also said he needed to look at the details of the North Korean offer.

The White House said it was unclear whether North Korea was seeking, in exchange, sensitive foreign rocket-launch technology for its claimed space program.

On July 20 Pentagon spokesman Kenneth Bacon suggested that Washington would consider launching North Korean satellites, but rejected providing North Korea with rocket boosters to put its own satellites into space.

Washington has used the perceived missile threat from Pyongyang to justify its plans for a 60-billion-dollar National Missile Defense (NMD) scheme, which is bitterly opposed by Russia and China.

Cohen, who will appear at a hearing of the US Senate Committee on Armed Services to talk about the NMD program on Tuesday, said that he will make a recommendation on the program in "about three or four weeks."