James Pattison's recent contribution ("The Ethics of Arming Rebels") addresses head-on a conundrum that has bedeviled the Obama administration. Reluctant to abandon completely the ideas of liberal internationalism, yet also very cognizant of the U.S. public's deep unwillingness to commit American forces abroad in the service of humanitarian ideals, the default position has always been to find local actors willing to carry out the fight with American-provided tools and limited assistance (such as trainers, use of air power assets, and so on). Indeed, a hallmark of the Obama administration's tenure has been the search for a low-cost/no-U.S. casualty model for humanitarian intervention. Successor administrations are likely to continue along this path given the polling data that suggests Americans remain extremely loath to commit U.S. forces for such operations. Thus, any call that "that arming rebels is generally impermissible and only exceptionally morally permissible" is, at worst, likely to fall on deaf ears in Washington.
At best, it will continue efforts to rebaptize rebels as the legitimate bearers and exercisers of national sovereignty. This of course was the approach taken in Libya, aided by the temporary willingness of different opposition groups to come together in an umbrella coalition to claim the mandate of popular sovereignty (and to be recognized as such by some of the intervening powers). This task has been made far more difficult in Syria by the fractious nature of the anti-Assad groups.
A different ethical debate is also underway when it comes to rebel groups—whether in Washington, Moscow, Paris, Ankara or Riyadh. That is whether or not the arming state has an obligation to assure its proteges of victory. Having encouraged rebels to continue to fight by providing weapons and financial support, do the sponsors have the duty to ensure their side can actually win and take power? The unwillingness to take on this burden has been one of the reasons the United States has hesitated to fully support different rebel groups inside of Syria. But it is clear that the ethical calculus is quite different and is based on assessments of likely success or outcomes that support U.S. preferences.