The launching of a nuke to strike at the satellite network is a bit beyond the technical abilities of most "terrorists." The concern lies in a state using them in a terrorist fashion (Iran, NK, or perhaps Pakistan). They have the techno to do it.

It is not beyond the capability of anyone with enough moxie (and money) to detonate a nuke in DC. Just look at the freakin truck traffic in the city.

Could you detonate it really close to the WH or Capital? Probably not. But you could take out the Lincoln Memorial, or the Washington Monument, or a host of other areas.

The point in detonating a nuke in DC wouldn't necessarily be the resulting damage (which would still be significant), it would be to show you could do it.
And since our southern border is pretty leaky...