Nuclear security around the world has improved dramatically over the last three decades—which demonstrates that with focused leadership, major progress is possible. But important weaknesses remain, and the evolution of the threat remains unpredictable. The danger that terrorists could get and use a nuclear bomb, or sabotage a major nuclear facility, or spread dangerous radioactive material in a “dirty bomb,” remains too high. The United States and countries around the world need to join together and provide the leadership and resources needed to put global nuclear security on a sustained path of continuous improvement, in the never-ending search for excellence in performance.

This is the final installment of a five-part series exploring the painstaking diplomacy and intelligence efforts that led Libya and its quixotic leader, Muammar al-Qaddafi, to relinquish that country's weapons of mass destruction.

This is the third installment of a five-part series exploring the painstaking diplomacy and intelligence efforts that led Libya and its quixotic leader, Muammar al-Qaddafi, to relinquish that country's weapons of mass destruction.

This is the second installment of a five-part series exploring the painstaking diplomacy and intelligence efforts that led Libya and its quixotic leader, Muammar al-Qaddafi, to relinquish that country's weapons of mass destruction.

The first installment of a five-part series exploring the painstaking diplomacy and intelligence efforts that led Libya and its quixotic leader, Muammar al-Qaddafi, to relinquish that country's weapons of mass destruction.

In the lead-up to the nuclear security summit, Advancing Nuclear Security: Evaluating Progress and Setting New Goals outlines what was accomplished in a four-year effort launched in 2009 to secure nuclear material around the globe—and what remains to be done. The effort made significant progress, but some weapons-usable nuclear materials still remain “dangerously vulnerable." The authors highlight the continuing danger of nuclear and radiological terrorism and call for urgent action.

William H. Tobey, and Matthew Bunn presented "The Non-State Actor Nuclear Supply Chain" at the Workshop on “Cooperation to Control Non-State Nuclear Proliferation: Extra-Territorial Jurisdiction and UN Resolutions 1540 and 1373” sponsored by the Nautilus Institute for Security and Sustainability on April 4 and 5, 2011.