This would be an interesting to see how the US would respond to a provocation from North Korea if they did in fact ever shoot down or even attempt to shoot down a US satellite:
North Korea’s main propaganda outlet claimed Wednesday that the recent midair explosion of a ballistic missile was intentional, calling it a test attack on enemy satellites.
North Korea’s Musudan intermediate-range ballistic missile was detected to have burst into pieces midair after flying some 150 km after its launch on June 22.
North Korea fired off another missile hours later, which soared to an altitude exceeding 1,000 km and flew some 400 km before landing in the East Sea.
The first missile launch seemed to have ended in failure.
Still, North Korea’s main propaganda website, Uriminzokkiri, claimed Wednesday that the midair explosion of the first missile was carried out by a control device installed in the missile and was not an accident.
The website also claimed that North Korea could render U.S. spy satellites lumps of scrap metal if Pyongyang detonates an electromagnetic pulse bomb at a high attitude after delivering it via one of its missiles. [Yonhap]
You can read more at the link, but if they ever did detonate an EMP in the air it would render far more than US satellites ineffective and likely cause a global movement for regime change in North Korea as an aftermath. That is why I think if they do an EMP capability that it would only be a weapon of last resort.