The case for military intervention in Libya rests on the principle of a "responsibility to protect" (R2P), which emerged from the international community's failure to prevent genocide in Rwanda in 1994 and ethnic cleansing in the former Yugoslavia between 1991 and 1995. R2P justified Nato's bombing campaign against Slobodan Milosevic's Serbia in 1999. It also informed no-fly zones in Iraqi Kurdistan and over southern Iraq between 1991 and 2003. Failure to intervene in Rwanda and Bosnia until very late illustrated the moral and human costs of the alternative and cemented Western nations' resolve to intervene in future to stem the tide of humanitarian disasters. But the record of R2P is not one of unmitigated success. 

Iraq's no-fly zone illustrated the limits of humanitarian intervention. Not prepared to put boots on the ground for fear of casualties, lack of an international mandate and support from domestic audiences, governments have usually undertaken these campaigns without the specific aim of removing the ultimate cause of evil they purport to prevent.

It is too early to assume that Libya will become a Mediterranean version of the Iraq no-fly zone. But it is not too early to notice similarities — namely, that in the rush to protect civilians, decision-makers have repeated a number of mistakes that in the past ended up tainting humanitarian interventions. By prioritising international consensus, Arab backing and UN endorsement over an effective, well-planned strategy, those governments now engaged in enforcing the no-fly zone failed to recognise that:

• The amount of military force they set out to use may not achieve their goals; 
• The mission may last longer than hoped; 
• Mounting costs and casualties will have repercussions far outweighing the benefits; 
• Only a larger commitment of forces on the ground will end up producing a decisive resolution to the conflict.

Western powers involved in this latest round of military action have spent considerable time and diplomatic resources seeking to build the kind of international support needed to pass the legal tools that would offer legitimacy to their intervention. They thus succeeded in getting a UN Resolution and even the Arab League's temporary backing for action. But these efforts have come at the expense of rallying sceptical allies around a set of policy options that could maximise success while minimising risk. There is no guarantee that the initial international support once prized so much more than allied backing will remain.