No defense, just offense. A war of utmost violence and lethality, scores of cities rendered as helpless as Katrina with no one to come to their aid, survivors largely involved with burying the dead,  a level of devastation for which we have no human experience, SAC pilots so traumatized by the sight of thermo-nuclear fireballs that 8% would simply bailout rather than continue, off continent fallout so intense that ships in the Med would suffer causalities, one minute you’d walking down the street the next enveloped in a fireball of unbearable heat with a glimpse no more of your impending death; one minute they’re walking with children, the next a child is trying to pass water to the corpse of her mother.  Returning SAC bombers find so little left that they would land on dry lake beds, SAC itself would be so shot up, so destroyed, crashed without gas, blasted out of the air by nuke-tipped missiles that what remained of SAC would be relegated to flying cargo; a landscape of smoking radiating ruins with 30 to 80 million dead, there would be no armies, no navies, no air forces to command; there would be no invasions or occupations, it would simply be annihilation. 

Or deterrence would work.