The Rove Doctrine
It certainly didn't come from the Iraq Study Group.
It most definitely didn't come from the voters in November
Nor did it come from either the old or new Congress.
We also know that it didn't come from Bush's (most recent crop of ex-) generals, whom he famously consulted on his "listening tour" across town.
But if all of the informed parties that Bush went to for advice were against escalating troop levels, then how could he have possibly come to such a decision? As Sherlock Holmes said, "Eliminate all other factors, and the one which remains must be the truth."
Thus, we are left with one option: Karl Rove. The "new strategy for Iraq" is not (as it might appear) actually a new strategy for fighting the conflict in Iraq, but rather a new strategy for fighting the politics of the Iraq issue. This is the only light in which escalation makes any sense, and it has the advantage of being consistent with the behavior of the Bush administration since its inception.
It's consistent with Bush's repeated framing of any issue in terms of what "message" it "sends." It's consistent with formulating governmental policy as whatever is most damaging to your political enemies. This administration habitually equates criticism of such policies as warrantless wiretapping, indefinite detention, and torture, with refusal to conduct terrorist surveillance. He publicly and repeatedly stated last Fall that voting for Democrats equated to voting for terrorists.
It has been long pointed out that this administration, unlike any to previously occupy the White House, does not "do" policy. Rather, policy decisions are routinely framed as political decisions. What best plays to the base? What's most damaging to the other party? What "sends the right message?" That's the Rove Doctrine, in one phrase.
This is how you get to escalation in spite of every informed opinion on the subject of Iraq: It's not about Iraq at all, and it never was. It's about us.