re: does the US need overarching strategy to confront Islamist terrorism?

While the obvious answer to your question is yes. It is a useless answer, and developing a strategy is futile until the U.S. defines the purpose, or objectives, the strategy is intended to achieve. Even Hillary Clinton recognizes that the U.S. under Obama does not have realistic purposes for its foreign policies. Don't do stupid stuff doesn't lead itself to developing effective strategies since it is a more reactive, rather than proactive, approach.