U.S., Soviets to Discuss Nuclear Test Verification

The United States and the Soviet Union have agreed in principle to discuss problems of verifying underground testing of nuclear weapons, Administration officials said today.

The discussions, probably later in the summer, would be the first under the Reagan Administration with the Soviets on ways to make sure limits set by an unratified 1974 treaty were being observed.

The United States would hope to gain from the talks “some sort of technically acceptable means of inspection,” said one of the officials, who demanded anonymity. He said this would call for some form of on-site inspection of Soviet testing facilities.

The Administration has proposed that the Soviets allow monitors to sink cables that would record the force of test detonations, but the procedure, known as CORTEX, has elicited little interest in Moscow, the officials said.

President Reagan, in a report to Congress, has accused the Soviets of exceeding the limit of 150 kilotons on underground tests, the only nuclear weapons blasts still permitted after the two sides signed a treaty in 1963 prohibiting testing in the atmosphere, outer space and under water.

Soviet leader Mikhail S. Gorbachev has tried to persuade Reagan to cease underground tests as well, but Kenneth L. Adelman, the director of the U.S. Arms Control and Disarmament Agency, and other senior officials say the tests are necessary to make sure U.S. nuclear weapons are safe and effective.