Among the more disappointing aspects of the career of the late Colin Powell is the extent to which, by supporting the invasion of Iraq in 2003, he contradicted his own eponymously named Powell Doctrine. That doctrine is of 1980s vintage and reflects the U.S. military's and Powell's own experience in Vietnam. The gist of the Powell Doctrine is that one should only go to war if all other alternatives have been exhausted, if there is a clear and obtainable objective, and if there is a plausible exit strategy. A corollary is that one should stick to missions that are clearly within the military's skillset--namely blowing stuff up and killing people--and avoid 'mission creep' at all costs. Also, the war should enjoy clear domestic and international backing. After our defeat in Afghanistan and putting up with all the vagaries of the "Global War on Terror," in which the Defense Department commonly has confused means with ends and set nebulous objectives, the Powell Doctrine has never looked more attractive. The problem is that it speaks to a simplistic view of conflicts, one in which one can achieve the desired result through a discrete and limited application of force. We go in, we do what we need to do, we get out. "Mission accomplished," as Powell's boss, President George W. Bush, notoriously put it. Would that this were always the case. Some conflicts quite simply require the sustained application of force, and they might never be resolved through any sort of military "decision." A rough analogy would be managing a chronic illness as opposed to a surgical intervention to deal with an acute problem. A strict application of the Powell Doctrine quite simply is too limiting.
The part of the Powell Doctrine that absolutely should be embraced is his insistence on the costs, benefits, and risks of a conflict being fully and frankly assessed. Implied in this requirement is the need to articulate precisely and honestly what a military intervention would entail, and whether or not a rapid decision is possible let alone probable. For example, the "forever war" scenario many assume to be categorically bad is not. Long-simmering conflicts might in fact be the best option. Some conflicts might simply require a lot of time. What matters is that all involved are clear about the nature of the conflict and the associated risks. Then debates can be informed ones.