Christopher Fettweis makes an interesting observation in the introduction to his book, Pathologies of Power:

Second, pathologies often help policy makers justify action at times when no vital, tangible interests are otherwise at stake. When pathology defines reality, policies become the opposite of what rational analyses of national interest would suggest is appropriate. As a general rule, the more leaders have to explain the motivation for an action, the less important it probably is….When war is truly necessary, it does not generally require justification or reference to often ill-considered beliefs. (p. 15)

Put another way, when war is justified it is not necessary to concoct elaborate rationalizations, and the more complicated and far-fetched the argument for war is the more likely it is that war is neither necessary nor just. This brings to mind the distinction between having a good reason to fight and coming up with excuses to do so. This seems to be a reasonably reliable standard for judging whether specific military actions are necessary. As we have seen in the Syria debate, hawkish arguments are often convoluted and frequently rely on invoking U.S. interests anywhere but in Syria. Intervention in Syria is deemed necessary to sustain “credibility” in order to reassure allies somewhere else. In this view, taking part in the conflict is important for the U.S. insofar as it “signals” to allies that the U.S. backs up its threats, including ones that it should never have made. Attacking Syria has also often been framed as part of a struggle over regional influence with Iran. Fettweis directly addresses this point later in the book and connects it with the desire for glory:

The hawkish senators and neoconservative commentators who call for intervention in the Syrian crisis, for instance, rarely fail to put it in context of the regional geopolitical struggle with Iran. To overthrow Assad would be to deal a blow to our regional enemy, to score points in the zero-sum game for influence over the region. The United States would win and Iran would lose, showering us with glory. (p. 235)

Fettweis is making a point here about how pathological beliefs define our Iran debate, but it applies equally well to the debate over Syria policy, which is shaped to a large degree by the preoccupation with inflicting damage on Iran. The U.S. doesn’t have tangible interests at stake in Syria (or Ukraine, as Fettweis pointed out last week), so some other excuse has to be found for getting involved. As we know from recent debates, preserving “credibility” is very often the preferred excuse. He says elsewhere that “there is a loose inverse relationship between the rhetorical employment of the credibility imperative and the presence of vital, tangible interests.” (p. 111) The less important a place actually is to the U.S., the more likely it is that we will hear that our “credibility” is on the line there. Indeed, Fettweis writes:

When credibility is the primary justification for action, it should be an indicator that the interest at stake is probably not vital to the United States. (p.112)

So whenever hawks invoke “credibility” to justify a more aggressive U.S. role in Syria, or Ukraine, or somewhere else, it should be taken as confirmation that no real American interests are in danger.