sentences:  The test projectile is fired under controlled conditions at a hard surface to measure the reactions and thresholds of different explosives to an impact.By 1979, the Los Alamos National Laboratory developed a new, safer type of explosive, called insensitive high explosive (IHE), for use in U.S. nuclear weapons; the physicist and nuclear weapons designer Ray Kidder speculated that the weapons in the Palomares and Thule accidents would probably not have detonated had IHE been available at the time.Denmark's nuclear-free zone policy originated in 1957, when the coalition government decided in the lead-up to the Paris NATO summit not to stockpile nuclear weapons on its soil in peacetime.