Nuclear tests per year, 1945–2026
Each bar counts the tests in one year; years after the selected one are faded. Drag across the chart to move the year; the map below follows. Click a milestone marker for the treaty or statement and its source.
Each bar counts the tests in one year; years after the selected one are faded. Drag across the chart to move the year; the map below follows. Click a milestone marker for the treaty or statement and its source.
Circle area = tests at the site so far. Dashed ring = tested in the selected year.
The United States has not conducted a nuclear explosive test since September 1992. Its weapons laboratories and test site now certify the stockpile through the Stockpile Stewardship Program, which Congress required in the 1994 National Defense Authorization Act "in the absence of nuclear testing".
"As a result of the voluntary moratorium on nuclear explosive testing the United States has observed since 1992, NNSA now ensures the reliability of the nation’s nuclear weapons through the Stockpile Stewardship Program. Comprising a wide range of scientific activities, from modeling and simulation to subcritical nuclear experiments, this program allows us to assess and certify the stockpile with extraordinary confidence."NNSA, Maintaining the Stockpile
"In subcritical experiments, chemical high explosives generate high pressures that are applied to nuclear weapon materials, such as plutonium. The configuration and quantities of explosives and nuclear materials are such that no nuclear explosion will occur."Nevada National Security Site, Stockpile Stewardship
Subcritical experiments take place more than 900 feet underground at the Nevada site's Principal Underground Laboratory for Subcritical Experimentation (PULSE), formerly the U1a Complex (NNSS history). They are not nuclear explosions and are not counted here. The November 2025 statement by the Energy Secretary quoted in the 2025 milestone described planned tests in the same terms.
Each bar is one year. Stack it by state to see who was testing, or by environment to see where: in the atmosphere, underground, under water, or at high altitude and in space. The environment switches and the yield classes in the panel filter every view at once, including the map and the counts.
The map places each test at its named test site, not at the coordinates of individual shots. Circle area grows with the number of tests at the site through the selected year. Tests at sea without a single site, and the Soviet peaceful nuclear explosions spread across dozens of locations, are listed under the map instead of plotted.
Yield classes use the upper bound of each published range, the same bins the U.S. used when it announced underground tests as "less than 20 kilotons" or "20 to 150 kilotons". Many yields were never published, especially for Soviet and Chinese tests; those sit in "Not published".
scripts/build_data.py: the Hiroshima and Nagasaki bombings are removed (2,049 rows remain); one Soviet 1972 underground test at Semipalatinsk, which the report's summary table counts but its itemized list lacks, is added with no date or yield; and North Korea's six tests (2006–2017) are added from the U.S. Geological Survey event catalog. Result: 2,056 tests, matching the ACA tally by state and by atmospheric versus underground.scripts/build_geo.py. All pages were opened on 2026-09-29.