The author examines the Proliferation Security Initiative--a multinational activity launched in 2003 to enable the United States and like-minded countries to interdict the flow of weapons of mass destruction (WMD). This Initiative also may bring dramatic changes the international security system by enabling concerned states to interdict international trade in WMD regardless of the location or nationality of their owners. As such, the Proliferation Security Initiative not only addresses one of the most urgent threats to peace and security that the world has ever witnessed, but it does so in an innovative way that has the potential to change the basic paradigm of peace and security by legitimizing the proportional and discriminating use of force to prevent a great harm. The author argues that the Initiative can be most successful by building broad support through increased transparency and a greater willingness to address forth-rightly the legal challenges that it faces.

"April 2006."

Introduction: the proliferation security initiative and its objectives -- The gravest danger : weapons of mass destruction -- How does the PSI work? -- Who is the PSI and what are they doing? -- Law and the seas -- United Nations and proliferation -- What can one man's army do? -- Conclusions and recommendations.