Methinks Niall doesn't quite get it. There is no need for "credibility" when you have the ultimate military force and a long and spotless history of utterly immoral and lawless behavior on your side. Our complaints about "human rights violations" or "violations of international law" have always lacked a scintilla of credibility because we have never considered them worth a second thought when "our" interests are at stake. If tomorrow's aggressors were to violate international law and/or commit gross human rights violations, the US would respond as it always has: if it's good for us, it's a defense of Freedom and Human Rights, and therefore the US government and the media will either publicly ignore it or support it with gusto; if it's bad for us, it's an outrage to be addressed with no little haste, the braying editorials hot on the heels of our cruise missiles.
Bill