He denies that he failed in Syria:
"It is very difficult to imagine a scenario in which our involvement in Syria would have led to a better outcome, short of us being willing to undertake an effort in size and scope similar to what we did in Iraq. And when I hear people suggesting that somehow if we had just financed and armed the opposition earlier, that somehow Assad would be gone by now and we’d have a peaceful transition, it’s magical thinking.
“It’s not as if we didn’t discuss this extensively down in the Situation Room. It’s not as if we did not solicit—and continue to solicit—opinions from a wide range of folks. Very early in this process, I actually asked the C.I.A. to analyze examples of America financing and supplying arms to an insurgency in a country that actually worked out well. And they couldn’t come up with much. We have looked at this from every angle. And the truth is that the challenge there has been, and continues to be, that you have an authoritarian, brutal government who is willing to do anything to hang on to power, and you have an opposition that is disorganized, ill-equipped, ill-trained, and is self-divided. All of that is on top of some of the sectarian divisions. . . . And, in that environment, our best chance of seeing a decent outcome at this point is to work the state actors who have invested so much in keeping Assad in power—mainly the Iranians and the Russians—as well as working with those who have been financing the opposition to make sure that they’re not creating the kind of extremist force that we saw emerge out of Afghanistan when we were financing the mujahideen.”
While Obama does not mention the contrasting views of some of his own advisers as well as many in the Congress, I think Syria posed too many dilemmas for U.S. policymakers. Advocates of overthrowing Assad had to rule out American "boots on the ground" and had to pretend that U.S. aid could be channeled only to "moderate" rebels with no risk of weapons or power going to extremists.
There are more comments in "outtakes" from the interviews that Remnick has now posted.