-LRB- CNN -RRB- -- The story of how I became a national figure in the media is widely known , but few people know what I actually did for the CIA . I was a covert operations officer specializing in nuclear counter proliferation -- essentially , making sure the bad guys did n't get the bomb . My job was to create and run operations that sought to peer into the procurement networks and acquisition chains of rogue nations . It was intense , tactical , creative and demanding . I believed that there was no more important work to be done . I resigned from the CIA in 2006 because it was no longer possible to do the covert work for which I was highly trained and which I loved . This happened because in 2003 , my covert identity was revealed in retaliation against my husband , Ambassador Joe Wilson , who wrote an op-ed piece in which he accused the White House of distorting the intelligence that was used to draw us into the Iraq war . But I did not lose my belief that the danger of nuclear terrorism was the most urgent threat we face . Nor did I lose my passion for working , albeit in a new way , to address that threat . I am working on this issue now as part of the international Global Zero movement , in which political , military and faith leaders , experts and activists strive for the worldwide elimination of all nuclear weapons . We know that terrorist groups have been trying to buy , build or steal a bomb . In the past two decades , there have been at least 25 instances of nuclear explosive materials being lost or stolen . There is enough highly enriched uranium , or HEU , in the world today to build more than 100,000 bombs . Terrorists looking to buy or steal HEU could look to the approximately 40 countries with nuclear weapons materials . And then there are rogue individuals out there who are running black markets selling nuclear materials and technology . Pakistan 's Dr. A. Q. Khan did it for years before my group at the CIA brought him down in December 2003 after catching him red-handed selling a full-scale nuclear bomb to Moammar Gadhafi 's regime in Libya . If terrorists manage to get their hands on enough HEU , they could smuggle it into a target city , build a bomb and explode it . A hundred pounds of highly enriched uranium could fit in a shoebox , and 100,000 shipping containers come into the United States every day . The nuclear threat is not limited to terrorism . There are also the dangers of proliferation and accidental or unauthorized nuclear launch . Today , nine countries have more than 23,000 nuclear weapons , and the U.S. and Russia still maintain thousands of nuclear weapons on hair-trigger alert , poised for launch within a few minutes . The only way to eliminate the danger that nuclear weapons will be used by countries in conflict , by accident or by terrorists is to lock down all nuclear materials and eliminate all nuclear weapons in all countries : global zero . Today we have a real opportunity to set the course to global zero . U.S. President Obama and Russian President Dmitry Medvedev , whose countries have 22,000 nuclear weapons or 96 percent of the world 's stockpile , are signing an agreement to reduce their strategic nuclear arsenals by a third each . This is the most significant arms reduction treaty in two decades and a crucial first step . Next week , Obama is hosting the leaders of 48 countries at a summit in Washington to address the global nuclear threat and initiate programs to secure all nuclear materials worldwide . With the U.S. and Russia leading the way , 2010 could mark the beginning of the end of nuclear weapons . But achieving global zero will take years , a realistic plan of action and tremendous amounts of political will . In February , leaders of the Global Zero movement met in Paris , France , and outlined a step-by-step plan to eliminate all remaining nuclear weapons . The plan , backed by hundreds of former heads-of-state , foreign ministers , national security advisers and military commanders , calls in its first phase for the U.S. and Russia to cut their arsenals to 1,000 total warheads each . All other countries with nuclear weapons would freeze their arsenals , and the international community would conduct an all-out global effort to block the further spread of nuclear weapons and to secure all nuclear materials . Locking down nuclear bomb-making materials involves building secure facilities for storage , accounting for all stockpiles , guarding materials in transit -LRB- transportation being the most vulnerable to terrorist attack and seizure -RRB- , regulating exports , interdicting smuggling operations , ending production of new bomb materials and ultimately eliminating existing stockpiles . These steps would be followed by the first multilateral negotiations in history for reductions by all nuclear weapons countries . I 'm proud to be working with the Global Zero movement and its team of world leaders and grass-roots organizers , presidents and college kids . I want to do everything I can to raise public and political support for the elimination of nuclear weapons . And that is why I said yes when Lawrence Bender , producer of `` An Inconvenient Truth , '' `` Good Will Hunting '' and `` Inglorious Basterds , '' asked me to be in an extraordinary and chilling documentary film , `` Countdown to Zero , '' which premiered in January at the Sundance Film Festival to critical acclaim and will be released in U.S. theaters in July . The film will be a stunning wake-up call to citizens and our political leaders about the urgent threats posed by nuclear weapons , including proliferation , nuclear terrorism and accidental nuclear launch . It will build awareness and support for the Global Zero movement to eliminate nuclear weapons . Based on my experience in the field , I believe that if governments do n't act now to begin eliminating all remaining nuclear weapons , we will witness in our lifetime the use of the bomb by a country or terrorist group . To get governments to act , everyone needs to get involved , to make their voices heard , to bring this issue to the top of the political agenda , to everyone 's kitchen table and to the front pages of every blog and every newspaper . There is still time to change direction and set our course to global zero , but the clock is ticking . To learn more about the issue and get involved in the growing movement , go to globalzero.org and sign the declaration . The opinions expressed in this commentary are solely those of Valerie Plame Wilson .