Turkey should have been leaned on very hard and made to act. The financial backers of ISIS need to be overthrown and replaced with more supportive people. If not, the contagion will spread and the world will be faced with allowing a Global Caliphate to expand and grow or dealing with it with the necessary severity and precision.
Our leaders lack cojones; they lack commonsense, and those directing them and allowing all of this to happen, are evil and have taken leave of their senses.
None of this suggests even a proper tactical response, let alone a strategy, unless it is to allow ISIS to grow until the conditions are right for a World War.