when is hard too hard?

Jim Steinberg, who served as deputy national security adviser and deputy secretary of state, has said that senior officials can rarely say a problem is too hard. They have to make choices despite uncertainties. The press and public often expect presidents to do something when tragedies are occurring abroad.

That also seems to be the philosophy behind a blue ribbon conservative think tank report by the American Enterprise Institute and the Institute for the Study of War. They call, like just about every other commentator, for an American "grand strategy" to deal with ISIL.

Sounds good, But they also note these problems:

Turkey, Saudi Arabia, the U.S., and Europe agree only that ISIS and al Qaeda are threats against whom action must be taken. They disagree on the importance of those threats relative to other national security interests and objectives. They disagree on the means by which to address those threats. Their desired endstates in Syria and Iraq diverge profoundly and are, in
fact, mutually-incompatible with one another and with ours. They even have opposing visions of the relationship of external states to the region.

So:

Situations in which all major states agree on goals and means are extraordinarily rare. This fact makes a hard problem harder, but it does not make finding a solution impossible. It does mean that Americans and Europeans must be prepared to immerse themselves in the complex local, regional, and international dynamics of Syria and Iraq and stop seeking arms-length answers through precision strikes or premature and ill-prepared negotiations. It also means that we must gird ourselves for a long involvement with these problems. That is not to prejudge whether American or allied military forces will be required or, if so, in what numbers and for how long.

Well, they seem to rule out the recommendations by most of the presidential candidates. But their own preferred courses of action won't be disclosed until a later report.