An easily identifiable feature of each item, such as a factory marking or registration number, will be recorded. The number will then be checked periodically. Sandia is also working on aerial inspection technologies. An Open Skies agreement that would allow overflights was stalled for some time because the Soviets objected to the prospect of U.S. planes flying over Soviet territory. Before the Soviets' recent change of position on flights by foreign aircraft, Sandia began designing a radar that could be mounted in other nations' aircraft without fear of giving away technical secrets.
Secrecy is even more vital when it comes to nuclear weapons.
Both the United States and the Soviet Union are worried that powerful scanning machines might reveal warhead design secrets. Until the U.S. reduced the machine' s capabilities, the Soviets refused to allow the Cargoscan X-ray to be installed at the Votkinsk perimeter portal installation. Argonne suggests that narrow beams of gamma rays could be shot through weapons to an array of receivers on the other side. The International Atomic Energy Agency uses this method to examine fissile material stored at civilian power plants. Neutron detection may also be used in chemical weapon verification.