"The Proliferation Security Initiative (PSI) is now three years old. Initially, 11 nations pledged their cooperation in interdicting shipments of weapons of mass destruction-related (WMD) materials; more than 70 nations now support PSI. Many observers believe PSI's 'strengthened political commitment of like-minded states to follow through' is a successful approach to countering proliferation, although details about PSI are sketchy. The 109th Congress has introduced eight bills supporting PSI. The State Department credits PSI with halting 11 WMD-related transfers from 2004 to 2005, and more than 2 dozen from 2005 to 2006. This report will be updated as needed."
CRS Report for Congress, RS21881