I've been working my way through the twelve points in this article about the War in Iraq.
The last three points aren't really amenable to the kind of historical approach I've limited myself to. However, when one looks at Iraq, the parallels with the 1970s conflict in the Lebanon are striking. A regime dominated by a minority has collapsed into civil war (Saddam + Sunnis = Lebanon's Christians; Shias = Lebanon's Moslems). The divisions are mainly confessional, but complicated by the presence of non-national force (the Kurds = PLO). Two external powers have strategic interests in the area (the United States + Iran = Syria + Israel). A foreign country has military forces occupying parts of the country, sponsoring a near-puppet government that perceives the occupier's interests as best-suited to preserving national integrity (the United States = Syria). Another foreign country intervenes in the conflict, directly supporting a confessional group (Iran = Israel).
There are also strong differences, most important being that Syrians regarded the partition of the Lebanon and Syria as an artificial one. There is no doubt that the United States does not regard Iraq as part of its national territory.
I have not quite taken a position in all this. Put simply, I thought the invasion of Iraq was a major blunder, said so at the time to anyone who would listen, and I haven't changed my opinion. However, now that the United States has so badly disrupted the lives of ordinary Iraqis, I hold it has a responsibility to bring a peaceful settlement to Iraq. Whether the Bush Administration is pursuing the best strategy to do so is debatable. But I'm not clear that a practical alternative has been proposed by anyone, which means I do not think an outright withdrawal is a practical alternative.