[Mike Darancette]

Iran or North Korea use a nuclear weapon on America through terrorist or a scud fired from a shipping container at sea. The USA nukes North Korea or Iran. Radiation spreads into China or Russia. In the interests of national security, Russia & China nuke the USA.

If we have already nuked NK or Iran what makes the ChiComs and Russkies think that we wouldn't launch on warning against them?

[iThinkBig]

"If we have already nuked NK or Iran what makes the ChiComs and Russkies think that we wouldn't launch on warning against them?"

Your point is the one of the exact reasons they may launch first.