Deter each other from attacking. north korea feels the nuclear weapons are the only way to protect their national sovereignty. they don't want to use them they say. however, if kim jong un were to feel backed into a corner, if there were some sort of misunderstanding or miscommunication there is always a chance, a very dangerous chance missiles could go flying and might hit their target is what these physicists are saying. we can't be a hundred percent sure missile defenses would be able to shoot even a few warheads down. that is a wager that the american public would want to make or would the...