Once termites start nibbling around the edges, the only way to stop them is to wipe them out. They don't have to be physically here to lob a nuke or other dirty device our way.
There are already enough "sleepers" ensconced on our ground to cause problems for some time to come - as we root them out, those in foreign lands will get itchy to find ways to attack - if we're totally reactive, we are saying that we are willing to sacrifice x-amount of American lives (Obama's policies) in order to not have to go where they breed.
It sucks, but reality is reality no matter how much we wish we could just mind our own business and let them do the same - they won't stick to themselves because it is their business to hurt us in any way they can.
Then you’d have to nuke many millions of people, possibly 1.6 billion people, because that is how many Muslims there are now on the planet (and growing very fast). Right now that is 23% of the world’s population.
Do you think the rest of the world would not have something to say about that, about us exterminating millions of people indiscriminately with nuclear bombs?