You think ISIS getting a hold of a nuclear bomb is impossible. For a while, they were bringing in over a million dollars per day. You assume that the tin pot dictator of N. Korea would be unwilling to sell such a weapon to ISIS? Maybe so. Would they be unwilling to sell one to Iran? Would Russia sell one to Iran? Would Iran, who currently sponsors Hezbollah be above giving that bomb to ISIS?
You still got to get the bomb to the US past our security. Is it doable? Maybe. If not here, then certainly hitting Europe or Israel is a possibility.
Maybe none of that is possible today. That does not make it impossible a few years in the future.
Who would have thought that Al-Queda could bring down the Twin Towers by taking over airplanes.
ISIS is only one concern of the many this country has, but to minimize it and put it on par with guns in the hands of toddlers is foolish.