Mike is spot on with his three points above. The contrast between theoretical viability of R2P and differing meanings is exactly why I cannot support it. It is much to easy for R2P to be perverted and abused.

Some comments have pointed to R2P as emanating from a State's responsibility to protect its own citizens. This, indeed, is the genesis of the theory. However, R2P expands that responsibility to the international community when a State is either unable or unwilling to fulfill its obligation. Thus, when the government of Libya, Syria, or Rwanda (pick a country) acquiesces in the breakdown in security for its population, the international community becomes burdened with that responsibility and should act to alleviate the suffering. From a moral standpoint, most would agree that the concept here is supportable. However, the tendency will always be to exceed that mandate.

In satisfying this new responsibility (new because the "social contract theory" is between a people to establish a government for their own protection; nothing is said about protection of outsiders to the contract), a State will invariably seek regime change. While this may certainly be required under the circumstances, the substitute regime will habitually be made in the same mold as the country conducting the R2P intervention, whether culture dictates it or not. Thus, the intervention morphs into a bellicose chauvinism wherein the populous of the country in which the R2P operation is conducted are "conquered into liberty" (see book of same title by Eliot A. Cohen) whether they desire our version of liberty or not. This brings about the nation-building that Mike correctly points out we are not particularly good at doing.

While there may certainly be instances in which regime change and nation-building are within our national interest (although I know of none currently), not every situation requires COIN-style rebuilding on our part. The realist in me believes we should do only that which serves our interests. R2P imposes burdens that may or may not do that, so we must resist it.