The United States today rejected a Soviet proposal for a joint moratorium on nuclear testing but invited the Kremlin to send a team of observers to Nevada to monitor a single American nuclear weapons test.
White House spokesman Larry Speakes described the U.S. invitation as an unconditional offer and said it was intended to demonstrate that the United States will "go the extra mile" to get results in the stalled nuclear arms control talks in Geneva.
Later, a senior Administration official revealed the Soviets had told the United States on Sunday that they would halt all nuclear testing unilaterally from Aug. 6 to Jan. 1, 1986.
The Soviets said they would extend the moratorium if the United States agreed to it, the official said.
In Moscow, Soviet Leader Mikhail S. Gorbachev announced the unilateral ban, to begin on the anniversary of the atomic bombing of Hiroshima, saying the arms race is an "immense threat to the future of the entire world civilization." He called the Soviet ban a step toward forging a fuller agreement on nuclear disarmament.
The U.S. official, who refused to be identified, said the United States rejected the moratorium idea. "I believe that the history of moratoria proposals document that they have been made for propaganda purposes," the official said.
The United States was notified of the Soviet plan Sunday, the official said, and notified Moscow of its invitation today. However, the official insisted that there was no link between the timing of the two proposals and said the United States had planned to make its announcement today, regardless of anything the Soviets did.
Speakes said there was no immediate Soviet response to the U.S. offer. "We look forward to a positive and timely Soviet response," he said.
Denying that the United States was trying to score a propaganda coup by making its invitation public, Speakes said: "It's not propaganda because it's backed up by facts that they can come. The invitation is there. This is not something that we're blowing smoke about."
Asked if there have ever been Soviet observers at an American nuclear test, Speakes replied, "I'm not aware of it."
Soviet Plan Not New
Speakes said he did not know whether the U.S. offer was limited only to the next, as yet unscheduled, underground test or whether it extended to "any test they choose."
Speakes said President Reagan, during his weekend at Camp David, had approved extending the invitation to the Soviets.
The Adminstration official said that the Soviet proposal was not a new idea and that a testing moratorium was in effect from 1958 until 1961. "You'll recall it was the Soviet Union who first resumed testing . . . with the largest series of high-yield explosions in history, including the largest single nuclear test ever conducted."
The official said the Soviet Union ended the moratorium with 40 atmospheric tests over a two-month period, and said that amounted to two years' worth of testing.