In his 2019 book The Back Channel, Burns has perhaps the best succinct summary of the Libyan decision to eliminate its WMD Programs:

At that moment in early 2005, the Libyan experience proved that diplomacy could accomplish significant changes in the behavior of difficult regimes. Of course it had to be backed up by other forms of leverage—many years of U.S. and multilateral sanctions; a solid international consensus, codified in UN Security Council resolutions; and the credible threat of force. It also mattered that we set consistent and achievable benchmarks for the negotiations on Lockerbie, terrorism, and weapons of mass destruction (WMD), delivered on our end of the deal, and over a period of years built up a fair amount of trust. Regime change was never the goal, and the Libyan leadership gradually developed a self-interest in changing behavior. It saw little benefit in winding up on the wrong side of the post–9/11 divide, and we provided a difficult but navigable pathway to a form of practical redemption. (page 309).