I'm against a "war on Islam" for all the obvious reasons, not least that my sister-in-law is Muslim. But let's assume the facts are these (I believe they are, but am not in a position to make an expert case for it):
The Wahhabi clerics of Saudi Arabia are behind the throne there, al Qaeda, and the Islamic State.
While the Saudi Throne is not directly in league with al Qaeda or the Islamic State, members of the extensive royal family, under the influence of the Wahhabi clerics upon whom the security of their throne depends, are.
The Wahhabi clerics, given the West's action to stymie al Qaeda, moved on to the Islamic State. If we block the Islamic State, they will metastasize, and create yet more groups to back.
Each Wahhabi metastasis gets more virulent: al Qaeda is worse than the Saudi dictatorshiip, the Islamic State is worse than al Qaeda.
Why are we not, then, openly at war with Wahhabi Islam? When evil wears the veil of religion, should that really prevent our effective response to their terrors?