Michael Tomasky worries  about a lack of national unity in support of foreign wars:
All the above amounts to a proper and essentially democratic skepticism. But that skepticism travels with a less healthy companion, a kind of civic cynicism that pervades almost all public questions these days. I have trouble conjuring up, for example, any event that could make us anything like the unified country we were during World War II.
There are at least two main reasons why modern U.S. wars so rarely produce that sort of unity. The first is that the U.S. mostly doesn’t fight necessary wars in self-defense, but chooses to join or start wars that have at most a tangential connection to our security. Some are entirely unrelated to American security, and some may even do real harm to that security. No matter how defensible a military action may be, there is never going to be the same degree of support for a war of choice as there is for a war fought in self-defense, and many of our wars of choice haven’t been very defensible.
The other reason is that the enemies that the U.S. has fought over the last thirty years have not required anything close to the sort of total mobilization that the country went through in WWI and WWII. In almost all respects, that is an undeniably good thing: it means that the threats we face today are much smaller and more manageable than the ones our ancestors faced, and it means that most of our society can continue to function more or less as it normally does. Besides, it makes no sense to demand widely shared sacrifices to combat third-rate dictatorships and low-level insurgencies, and it is impossible to expect unity in support of war efforts that are neither necessary nor wise. It is also very difficult to maintain broad support for a war that doesn’t seem to have any clear purpose or discernible conclusion. No sane nation would remain unified in support of pointless wars that last a decade or more, and no one should want them to. One other reason why this degree of unity is unlikely nowadays is that Americans have generally become less accustomed to deferring to political leaders and more inclined to assume that we are being taken for a ride and misled into unnecessary dangers. All things considered, I’m not sure that this is such a bad change, since our leaders often do abuse the public’s trust and don’t deserve to be given the benefit of the doubt on such important matters.
As Tomasky will remember, there was a remarkable degree of unity in the weeks and months following 9/11 and during the earliest phase of the war in Afghanistan. That attitude prevailed as long as the main U.S. military effort overseas was directly related to responding to the attacks on the U.S. There was overwhelming support for that effort, and it is likely that this would have continued without much change for at least a few years. Once the debate over invading Iraq began, that unity started to fracture for obvious reasons. The Iraq war was completely unrelated to the attacks, and it represented a huge diversion of attention and resources into a new and unnecessary conflict. The public rallied behind the administration in 2002-03, but found that it had been sold a bill of goods and belatedly discovered that the short, cheap, and easy war that they had been promised had turned into an open-ended, expensive, and bloody conflict. The last time that the public offered broad, largely uncritical support to U.S. foreign wars, their trust was betrayed and the country was much worse off because of it. We shouldn’t be worried about a lack of unity in support of our foreign wars. We should be more concerned with avoiding the unnecessary ones, of which the current war is just the latest.