Why Bush went to Vietnam (in his speech. not for real, of course.)

The reason the White House suddenly shifted to comparing Iraq to Vietnam is well revealed in this AP article, "Iraq report may bolster surge policy."

Among all the disasters and bleak outlook in the NIE, the only element that can possibly be extracted to support current policy is "A change of mission ... would place security improvements at risk."

The White House knew the NIE was going to be declassified and knew the contents. The White House is actually writing the "Petraeus" and "Crocker" reports. They went to this Vietnam analogy of disaster on leaving because it is the only semi-externally supported defense continue their policy.