https://en.wikipedia.org/wiki/Nuclear_blackout https://en.wikipedia.org/wiki/Nuclear_blackout > it moved to the UHF region to help mitigate this effect.[16] E

https://en.wikipedia.org/wiki/Nuclear_blackout https://en.wikipedia.org/wiki/Nuclear_blackout > it moved to the UHF region to help mitigate this effect.[16] Even then, it would be heavily attenuated.[7] > This means that exoatmospheric explosions are very effective against long-range early-warning radars like PAR or the Soviet Dnestr. A single 1 Mt warhead detonated at 250 km altitude would be about 600 kilometres (400 mi) downrange given typical trajectories, and might be expected to create an ionization disk 300 kilometres (200 mi) across. As seen from the radar, this would be an angle of (300 km/600 km)2 ≈ 0.3 sr, enough to hide any warheads approaching along similar paths. This would allow, for instance, a single warhead from a particular missile field to hide all the following ones from the same field. Although this would not affect the operation of the interceptors directly, being outside the range of even the very long-range Spartan, such operations could seriously upset raid direction and overall battle planning. Moreover, because the explosion takes place outside the range of the interceptors, there is no simple means of stopping it.[8] There's also a lot of uncertainty meaning it might be much worse, that is describe on same link.