Cofty,
Harris explored the hypothetical situation where an Islamic state obtained long-range nuclear weapons.
You cannot eliminate ISIS with a nuclear bomb. Eliminate the bomb perhaps but not the organization. Also, they would have to experiment dozens of times in order to get a reliable ICBM with a functioning nuke. That can be dealt with by non-nuclear means long before it's completed.
North Korea, which continues to develop its short range missile technology has yet to miniaturize its nukes so that they can fit into a missile of any size or range.