[phreazkzaway]

That would trigger an overwhelming response.

Nuclear weapons create huge EMP bursts which disrupt communications. One popular type of theoretical first strike is to detonate one or two missiles in the atmosphere to cause confusion, then follow up with the main salvos while peoples' main sensors and communications are blind.

[throwawaybutwhy]

_High-altitude_ explosions create EMP. And nuke yield can be dialed down to Hiroshima levels.