Charles Glass has an excellent post on the London Review Blog, worth reproducing in full:
The Libyan dictator is resisting the popular forces ranged against him in ways that his counterparts in Tunisia and Egypt did not. In Tunis and Cairo, Zine Abedine Ben-Ali and Hosni Mubarak were the faces of military regimes. Colonel Muammar Gaddafi is not the face: he is the regime. The Egyptian and Tunisian army chiefs calculated that sacrificing their nominal commanders-in-chief would preserve their own positions without jeopardising the interests of their American benefactors. Playing the role of saviours of the nation, after years in which the officer class enriched itself and ordinary soldiers were made to repress dissent, the armies in Tunisia and Egypt emerged as arbiters of whatever order will follow the post-dictator era.
Since Gaddafi seized power in Libya with his co-conspirator Major Abdul Salam Jalloud in 1969, he has remade the military in his own image to enforce his rule. In this, he enjoyed the successive support of the CIA, the Soviet Union and the East German security services. In Egypt, the army had some legitimacy from the Nasser era, when a whole generation of junior officers (all of whom entered the army after its officer class was expanded beyond the pashas in the 1930s) supported the revolution of 1952. When Nasser died in 1970 and Sadat was assassinated in 1981, the army set ground rules for transition that preserved its position. Libya, since Gaddafi overthrew King Idris, has never faced a transition. Gaddafi is not contemplating one, which leaves his army no option but to retain him. If he goes, they are finished.

