A dirty bomb is discovered Jan. 22, 2009, in a warehouse near London, launching an international crisis.

The bomb scare and other nuclear proliferation concerns prompt U.N. Secretary General Ban Ki-Moon to call an emergency-review conference of the Non-Proliferation Treaty (NPT), the world's central nuclear security agreement, at Stanford on Jan. 30-31. While the conference is under way, a second nuclear bomb is found in a shipping container near Frankfurt airport, and the government of Pakistan is overthrown in an extremist coup that establishes the Islamic Caliphate of South Asia.

More than 100 Stanford students enrolled in International Security in a Changing World confronted these political and diplomatic challenges during the course's annual mock exercise on nuclear arms control. Representing the governments of 22 countries, the students aimed to pass a consensus resolution to strengthen the NPT, which was drawn up in 1968 to limit the spread of nuclear weapons.

"The simulation helps you understand how a diplomatic experience really works," said former Ambassador Thomas Graham Jr., a senior arms control negotiator who has represented the United States during actual NPT review conferences. "The dynamic of issues clashing is an important learning experience for participants and observers. It leads to unexpected results that happen in real life."

Graham is a longtime participant in the simulation exercises that Scott Sagan, co-director of the Center for International Security and Cooperation (CISAC), created in the late 1990s. The exercises require students to study the political agendas and nuclear-weapons policies of different countries, and to dress, act and speak like diplomats. In addition to Graham, several CISAC members-including Martha Crenshaw, who is co-teaching the course; Pavel Podvig, acting associate director for research; Alex Montgomery, a visiting assistant professor; and Amandeep Gill, a visiting scholar-acted as heads of state to the student-led country delegations.

Kate Kuhns, former director of the Freeman Spogli Institute's Initiative on Distance Learning, also played a head-of-state role. Stanford Law School's Allen Weiner, an expert on international law, played the part of U.N. undersecretary-general for disarmament, and Josh Weddle, a law student, acted as U.N. assistant secretary-general. Knight Fellow Janine Zacharia, a real-life diplomatic correspondent for Bloomberg News, wrote wire stories during the conference that captured tense negotiations as the simulation unfolded.

"I was stunned by how real it felt," Zacharia said afterward. "It was just like the summits I've covered. I marveled at how well the kids embodied their roles, especially the Iranian and the Indian and the Arab state ambassadors."

Gill, a professional Indian diplomat who has served in Iran, also rated the exercise as fairly realistic. "Many of the dangers highlighted by the conference were chillingly close to actual nuclear dangers," he said. "Terrorist use of WMD, the continued threat of accidental or inadvertent nuclear war and the possibility of an extremist takeover of nuclear weapons in Pakistan."

Students, for example, stayed in character during the opening plenary when the Arab delegations stormed out of Kresge Auditorium, where the conference was held, to protest the participation of Israel as an observer in light of the military assault on Gaza.

In Kresge's foyer, Brazil's delegation head, junior Natascha Born, pleaded with the delegations of Saudi Arabia, Iraq, Iran and Syria to return to the conference. "This is counter-productive, you're losing bargaining power," she said. "What you are doing is denying democracy." Sophomore Akhil Iyer, representing Saudi Arabia, snapped back, "We have tried to cooperate [with Israel] for a number of years. We need to show an aggressive stance." Despite the walkout, other delegates voted to allow Israel to participate.

After two days of negotiations, the delegations passed a resolution to consider creating a multilateral organization to investigate the London and Frankfurt incidents. They also agreed to create regional nuclear fuel banks controlled by the International Atomic Energy Agency and establish a "Global Proliferation Security Initiative" to thwart nuclear smuggling. Finally, they called for nations to take concrete steps toward nuclear disarmament.

Gill, the Indian diplomat, called the agreement "a fairly plausible outcome," adding that what did not happen was equally instructive.

"I was surprised by how close were the constraints the delegations faced in pushing their agendas to real-life limitations on state options," he said. "An example was the U.S.-Indian attempt to take over the [caliphate's] nuclear arsenal, which was derailed by a coalition of regional and European states. I would rate the exercise as a valuable learning tool."