From Jake Sullivan (State Department Director of Policy Planning):

First, we have been taking this deadly seriously, as we should. I set up the ARB in record time, with serious people on it. I will get to the bottom of all the security questions. We are also in overdrive working to track down the killers, and not just through the FBI. We will get this right.

Second, the White House and Susan were not making things up. They were going with what they were told by the IC.

The real story may have been obvious to you from the start (and indeed I called it an assault by heavily armed militants in my first statement), but the IC gave us very different information. They were unanimous about it.