See tagline.
At this point, all I can think is that the Bush admin has concluded that until the election, Afghan/Iraq is all the nation will tolerate; and while we REALLY need to clean out Syria and Iran, there just isn't the public support there, even if we "discover" WMDs in Syria (courtesy of Saddam). It is a political reality.
Consider this: in 1942 we already had solid information that the Nazis were killing thousands of Jews in a systematic way. Imagine that the papers then were like they are now: in 1944, we go into France and Belgium . . . but no death camps; and in early 1945 we get into parts of Germany . . . but no murder camps. The public is saying, "Where are the camps?" In fact, most of the killing camps were not in the U.S. zone at all, but in the east, the Russian zone. Now, that didn't mean the camps didn't exist. It just meant they were in a zone other than where we thought we'd find them.