"China's population etc. is even more spread out, in some respects, than ours."
Why punish the population at large for the misdeeds of their leaders?
Why not simply evaporate the Communist Party leadership in their bunkers, and then let the warlords and bandits run things?
We MIGHT be able to do it
IF there was a surprise attack
ON OUR PARTS
WITH UFO TYPE CRAFT
AND WITH EXCELLENT INTEL
AND IF WE HAD THE WILL TO DO IT
AND IF THE PUPPET MASTERS ALLOWED US TO.
NONE of which will occur.
They will surprise attack us though probably elements of our nation and even of our military will know it ahead and be unable or unwilling to do anything significnat about it.