- The notion of "legitimacy" is a key one in US foreign policy toward adversary governments in countries that the US does not fear militarily (for example, because they have nuclear weapons). In the context of US foreign policy, the term "legitimacy" is a term of art that has a specific meaning. The usual notion of government "legitimacy" in international law and diplomacy, which the US applies to its allies without question, has nothing to do with whether we like the policies of the government in question or consider them just. Either you are the recognized government of the country, holding its seat at the United Nations, or you are not. Hardly anyone in Washington would suggest that the governments of Saudi Arabia, Bahrain, Jordan, or Israel are not "legitimate" because they were not elected by all of their subjects or because they engage in gross violations of human rights. Nor would many in Washington suggest that the governments of Russia or China are not "legitimate," however one might dislike some of their policies, their lack of democracy, or their violations of human rights. These countries have nuclear weapons and a permanent seat and veto on the UN Security Council, so challenging their legitimacy could have dangerous consequences. The US may complain about their policies, but there is no chance that it will challenge their "legitimacy."
and much more on Syria and wikileaks here