There have been significant improvements during the past decade in the worldwide ability to detect covert nuclear explosions equivalent to only a few hundred tons of chemical explosive, experts told a recent AAAS-organized discussion on Capitol Hill.

All but the most determined efforts at evasion likely would be spotted by a growing array of seismometers, radiation monitors, and other devices designed to detect nuclear blasts underground, underwater, in the atmosphere, and in space, they said.

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