Can a Christian Support War?

It seems to me that since the dominant image of Christianity in the US media is of right-wing Christians who predominantly vote Republican, one would think that this group would generally be in support of the current military operations in Iraq. On the other hand, I personally find that I cannot count myself as a follower of a Jesus who always practiced non-violence himself, and support violent actions of my state. Another view of the issue is that a Christian ought to support war if and only if every other possibility has been exhausted. So, perhaps this would make the Second World War justifiable, but one would want to let the inspections process finish before finally coming out in support of military action in Iraq. I have heard this called “Just War Theory.”

Must a Christian be a pacifist? Must a Christian support war in some cases? Is Just War Theory a workable solution to the problem? Are there other possibilities?