An Op-Ed piece by today's WSJ says something so obvious that it is amazing that some people refuse to get it.
Diplomacy only works when each of the negotiating countries has something to gain from a successful outcome. Then they can bargain and trade concessions. I'll give you lower tarrifs and you give me a better border security, or whatever. If one country simply wants the other country to do something and has nothing to offer, then the only thing it has is the credible threat of the use of force. You start respecting human rights or I'll invade your country.
Ghadhafi's capitulation was not a triumph of diplomacy. Behind the scenes was not something like: "You admit to blowing up airplanes, and starting a WMD program, and we'll let you hang out with us at the next UN shindig and spend millions trying to apologize for the past". It was more like "You do what we say, and let our inspectors wherever they feel like going, and only then will you not be the next person hiding in a hole, unshaven listening to your wife sell you out, while we kill the parts of your family that we missed last time and make your country a respectable humane place to be."
Moamar ain't dumb. He sees the decline of the hegemony of Arab values over Arab peoples. Pretty soon it will be Western values ruling Arab people, and he does not want to be there when it happens. It is only brute force that allowed us to capture Saadam and it was the threat of brute force combined with Ghadhafi's ego making him thinking he was important enough to be next, that scared him in to capitulating to the demands that he cool his WMD programs.