I Always Assume Everyone Knows Something I Don't

So Bechtel washing its hands of Iraq makes me think that the post-election scenario contemplated by Administration insiders is at best one of U.S. troops withdrawing into their cantonments and letting the Iraqis sort out their blood feuds on their own:

Bechtel Leaves Iraq After Losing 52 Workers in 3 Years

Since the Left seems to view all exercises of U.S. military instruments of foreign policy through the lens of Vietnam; it's worthwhile to consider whether such a cantonment scenario is sustainable. Would Speaker Pelosi not be likely to play to her base by routinely confronting the Administration on supplementals and authorisations so long as U.S. troops remain within mortar range of the Mahdi Army? Wouldn't this in turn lead to the effective withdrawal of U.S. troops from any role in the political violence in Iraq? And wouldn't this in turn lead to the very realisation of the self-fulfilling prophecy of U.S. involvement in the area ending in chaotic evacuation by helicopter from rooftops while the Iranian backed militia indulge in orgies of reprisals against anyone who ever had a good word to say about the U.S. in Iraq?