The point of my scenario is that the launches AREN’T hidden, and they don’t have to go off at exactly the same time. So what if the warhead over LA goes off 30 minutes after the the one over NYC? This is also not about maximum efficiency — Starfish Prime was only 1.4 megatons at 250 miles up. Ramp that up to 20MT. Honolulu was over 800 miles from the test site and was affected — what’s the spacing on the eastern seaboard between cities? Heck, even the entire west coast could be zapped with only three warheads.
The other point with EMP is no one dies — at least not right away. It’s so much more insidious than that. So at worst an EMP strike is like a major hassle, compared to an actual airburst over a city which is a massacre. No massacres here.
With CONUS and the Middle East crippled, the only reliable energy game in town is Russia. Do you think Germany would give a thumbs up to nuking it’s only gas supply? The US will need all of it’s allies help immediately to recover, they can’t afford to rage away when they have a country to repair and a population to feed and water.
No “Red Dawn” invasion here, this war is economic and diplomatic. It changes the power structure of the world overnight without a single city being razed. No soldier fires a shot.