A 1.5mt bomb exploded 250 miles over Kansas would effect the entire US. There are variables which could minimize the damage done on the coasts. Adding a second bomb would solve solve that problem.
250 miles over Kansas?
Called Nuke um from Orbit.
I am not convinced that anything less than 2 dozen weapons at high altitudes (nothing like 250 miles) would be necessary to completely destroy our power system and immobilize our population.
It is not a simple matter to evaluate. Depends on the device targeted and the weapon design. Not just Kiloton blast size. EMP weapons are low yield nukes in terms of blast. Frequency of pulse generated. distance does deteriorate the electromagnetic pulse. Especially outside out ozone layer.
This type of weapon is not a magic bullet.
And there is the question of what price the aggressor will pay in our retaliation. That is a serious deterrent. Unless Obozo is successful in reducing the numbers like he plans. Talk of reducing our inventory to 300 weapons. (all types) Insanity!