Since Bush has been re-elected and since there is no coherent "impeach Bush" movement, the issue of the wisdom of invading in the first place is pretty moot. (It will come up again in 2008, though.)

A Saigon-style rout seems most unlikely. That came about from a massive enemy attack by an army of hundreds of thousands, combined with the collapse of the South Vietnamese army. If American forces had still been in South Vietnam at the time, to the number of a quarter million or more, the collapse might have been averted or at least forestalled.

I'm not trying to suggest one way or the other whether they should have been there in the first place, simply that their continued presence in 1975 may have made a difference at that moment.

There are no enemy armies rolling through Iraq, and support for the insurgents seems to be limited. Similarities to Vietnam remain superficial only.

It would look good on paper to replace the U.S. military with some sort of ad-hoc international force, but besides being the most powerful on earth, the U.S. military is probably the best equipped in every sense to limit further chaos. One hopes that it will.