Um, but such logic is not always uppermost in people's minds. That is the worry. It only takes one irresponsible idiot to get his finger on the button (so to speak) and off we go. What if (as a wild example) Pakistan gets taken over by an ultra-something-or-other military clique. The have a war with, oh, China, or India. The war goes very badly. Ultra-nutty leader screams 'no peace with the enemy devil', but his enemy's troops are with his borders and advancing rapidly. So he takes a bold move - he uses a tactical nuke to eliminate an enemy column. And off we go.