This relatively easy-to-understand paragraph is from that article I mentioned below:
Civil wars are military contests where each side's military capacity shapes the type of military interaction and, therefore, the nature of the conflict. Both insurgent and counterinsurgent strategies vary accordingly, and yet their "lessons" are conditional on the prevailing technology of rebellion. For example, the combined experience of Iraq and Afghanistan has led the U.S. military to focus single mindedly on irregular war. However, the lessons of Afghanistan are not necessarily transferable to [a symmetric nonconventional] conflict such as the Somali one. Our analysis also implies that, as they consider peacekeeping and peace building operations, policy makers must be aware of the variation in technologies of rebellion, as well as the transformation of internal conflict after the end of the Cold War. For instance, neither conventional nor [symmetric nonconventional] civil wars correspond to the popular image of a quagmire associated with irregular wars, which have deterred international intervention in the past.
The question I would have for Kalyvas and Balcells would be the following: Yeah, this is all fine and good, but speaking in plain English, if the United States were to intervene in a conflict, might that external intervention change the conflict in unpredictable ways? Maybe it boosts the capacity of one party, and maybe a rival party (say, Iran) jumps in and boosts the capacity of another party. Maybe, before we know it, the conflict has morphed into a robust insurgency in which one actor is employing irregular means. And maybe policy-makers should internalize the lessons of Iraq and Afghanistan lest they lead the U.S. military into another, ahem, quagmire. Because the war in Afghanistan, to use one example, is not one conflict that you can code just once in some database but rather a series of conflicts that has been fought using a variety of "technologies" from 1979 to 2010. I myself saw a very different war in 2002 than the one I saw in 2004. And I saw an altogether new war in 2009 in large part because an external actor (Pakistan, in this case) jumped into the conflict in the five years between my second and third stints to Afghanistan and boosted the heck out of the capacity of the insurgent actors.
Another thing: if you really think something is important for policy makers to understand, why the hell write about it using highly specialized vernacular in a journal no actual policy maker reads? Please tell me this APSR article will be followed up by an article in International Security or, even better, in a paper for a humble policy-oriented think tank.
None of these questions, by the way, should detract from a really excellent article with potentially important implications.