And since 1963, most nuclear testing has been conducted underground, with no government that signed the treaty breaking the treaty. (France and China, both nuclear-armed nations, have not signed on to the limited test ban). When India and then Pakistan tested nuclear weapons in May 1998, they did so underground. Preparing a nuclear test this way generates the kind of activity that an intelligence agency should be able to pick up with months of above-ground site preparation visible in satellite imagery, but at the time the CIA managed to miss it. However, seismologists were able to find out about the tests almost instantly, and were able to determine both the location and the likely range of nuclear explosive power from the tests of Pakistan and India.