The 1987 Soviet nuclear tests were a series of nuclear explosions conducted by the Soviet Union following the termination of a unilateral moratorium on nuclear testing that had been in place since August 1985. The tests were part of the broader Soviet atomic weapons program and took place primarily at the Semipalatinsk Test Site (Kazakh SSR) and the Matochkin Shar Test Site (Novaya Zemlya, RSFSR).
Context: The 1985–1987 Moratorium On July 29, 1985, General Secretary Mikhail Gorbachev announced a unilateral suspension of nuclear testing, effective August 6, 1985, challenging the United States to reciprocate. The moratorium was extended several times, most recently in August 1986. Citing the lack of a reciprocal response from the U.S. and the continuation of the U.S. testing program, the Soviet leadership announced on February 5, 1987, that the moratorium would end.
Test Series The first test after the moratorium occurred on February 26, 1987. Throughout the year, the USSR conducted a total of 21 nuclear tests (some sources cite 22, depending on classification of zero-yield or safety experiments). This marked a significant increase in tempo compared to the pre-moratorium years.
Key characteristics of the 1987 series include:
- Locations: The majority were conducted at Semipalatinsk (Degelen Mountain and Balapan areas) and Novaya Zemlya.
- Yields: Yields ranged from low-yield (sub-kiloton) developmental tests to higher-yield weapons effects and verification tests, typically up to 150 kilotons (the Threshold Test Ban Treaty limit).
- Types: The tests included weapons development, weapons effects studies, and safety experiments (hydrodynamic tests).
- Notable Tests:
- February 26, 1987 (Semipalatinsk): The first test breaking the moratorium, yield reported approx. 3–10 kt.
- April 25, 1987 (Novaya Zemlya): A larger yield test, approx. 110 kt.
- October 18, 1987 (Semipalatinsk): A test associated with the "Kraton" (peaceful nuclear explosion) program or deep seismic sounding, yield approx. 2.3 kt.
International Monitoring and Verification The 1987 tests were closely monitored by Western seismic networks (such as the USGS and the Norwegian NORSAR array) and became a focal point for negotiations on verification protocols for the Threshold Test Ban Treaty (TTBT) and the Peaceful Nuclear Explosions Treaty (PNET). The resumption of testing complicated ongoing arms control talks in Geneva but also provided data for the eventual Joint Verification Experiments (JVE) conducted in 1988 at the Nevada Test Site (USA) and Semipalatinsk (USSR).
Subsequent Activity Soviet nuclear testing continued in 1988, 1989, and 1990. The final Soviet nuclear test (Test 1084) was conducted on October 24, 1990, at Novaya Zemlya. On October 5, 1991, Gorbachev announced a new unilateral moratorium, which was subsequently inherited by the Russian Federation and effectively made permanent with the signing of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in 1996.
