in 1960, george kistiakowsky introduced the "threshold principle" that balances the needs of arms control with the realities of seismic verification. he cited the difficulty in monitoring missile submarines, and proposed that the arms control strategy focus on disarmament rather than inspections into verification, which accepts that nations may do nuclear, or simulated nuclear, testing of an explosive yield below the energy level that seismic intelligence sensors can detect. all nuclear testing, of any level, was forbidden under the comprehensive test ban treaty (ctbt) (which has not entered into force), but there is controversy over whether the comprehensive nuclear-test-ban treaty organization (ctbto) or its preparatory commission will be able to detect sufficiently small events. it is possible to gain valuable data from a nuclear test that has an extremely low yield, useless as a weapon but sufficient to test weapons technology. ctbt does not recognize the threshold principle and assumes all tests are detectable.