Jon Chait musters more patience than I'm capable of, and explains why you sometimes need a law enforcement approach to terrorism:
[T]errorists often operate in our country, or in friendly countries, which makes military action against them tricky. McCain (through his campaign blog) assailed Obama for favoring "prosecutors rather than predators." But, when the terrorists are holed up in New York City, as was the case with the 1993 bombers Obama referred to, simply arresting them strikes me as more efficient than leveling their apartment with a drone-fired missile.
Now I suppose that knowing how conservatives feel about Western Europe and America's large coastal cities, maybe they do think we should be launching airstrikes in these venues and maybe we shouldn't be giving them ideas.