The recent election of Hassan Rouhani as president of Iran provides a new and important opening for the United States and its P5+1 partners to secure an agreement that limits Iran's nuclear capabilities in exchange for easing tough international sanctions.

While international diffusion of nuclear materials and technology is an important cause of nuclear weapons proliferation, experts disagree on how best to address the problem and prevent countries from acquiring nuclear weapons.

Experts described the achievements and problems in bringing down the Khan network and the changes needed to deal with pervasive illicit nuclear trade.

2007 Carnegie International Nonproliferation Conference Panel: Finding Innovative Ways to Detect and Thwart Illicit Nuclear Trade. Chair: Steve Coll, The New Yorker; David Albright, Institute for Science and International Security; Matti Tarvainen, International Atomic Energy Agency; Ralf Wirtz, Oerlikon Leybold Vacuum.