They definitely detect the explosions themselves, not just missile launches (remember that ballistic missiles are only one method of several for delivering nucl

They definitely detect the explosions themselves, not just missile launches (remember that ballistic missiles are only one method of several for delivering nuclear weapons). This is for monitoring compliance with nuclear test bans, as well as just generally knowing what is going on. If a nuclear weapon goes off for any reason, the US government and other nuclear powers obviously want to know about it. These systems would also be able to distinguish non-nuclear explosions such as bolides from nuclear explosions, which is important for MAD if you don't want an accidental war. The systems to do so are now built into GPS satellites. https://en.wikipedia.org/wiki/Vela_(satellite) https://en.wikipedia.org/wiki/Vela_(satellite) https://en.wikipedia.org/wiki/Nuclear_MASINT#Space-based_Nuclear_Energy_Detection https://en.wikipedia.org/wiki/Nuclear_MASINT#Space-based_Nuc... https://en.wikipedia.org/wiki/Global_Positioning_System#Military https://en.wikipedia.org/wiki/Global_Positioning_System#Mili...