I'm pretty sure that only applies to ballistic missiles though. Cruise missiles probably don't show up on those satellites, and even if they did, how would you differentiate a nuclear armed cruise missile from a conventional cruise missile? There is also the matter of nuclear torpedoes, bombs dropped from planes, bombs placed by special forces (https://en.wikipedia.org/wiki/Special_Atomic_Demolition_Muni...), nuclear artillery shells (https://en.wikipedia.org/wiki/W48), recoilless guns (https://en.wikipedia.org/wiki/Davy_Crockett_(nuclear_device)), etc.