“When the atom was split over Hiroshima and Nagasaki…we entered a new, terrifying era in which the annihilation of humankind suddenly loomed as a real possibility,” Mr. Annan said in a message to the General Conference of the Mayors for Peace, meeting in Hiroshima to mark the 60th Anniversary of the bombings that killed more than 100,000 men, women and children instantly, and condemned over 200,000 more to horrific and lethal sickness.“And yet, from that shadow, a new hope emerged. Recognition of our interdependence ushered in the United Nations and the concept of our collective security,” he said. But 60 years on, nuclear proliferation remains a pressing global challenge.“Tens of thousands of nuclear weapons remain; many of them on ‘hair-trigger’ alert…and the emergence of a nuclear black market and attempts by terrorists to acquire nuclear weapons and materials have compounded the nuclear threat,” he said.Urging the mayors to press ahead with their valuable work – building bridges of global cooperation at the community level, Mr. Annan said: “All States must do everything in their power to ensure that the horrors of Hiroshima and Nagasaki are not visited on any peoples, anywhere, ever again.”“I am heartened, therefore, that you are promoting your vision of a global ban on nuclear weapons by 2020. As representatives of the aspirations of peoples and communities around the world, as a link between the local and the global, you have a crucial role to play,” he added.The Mayors for Peace is composed of cities from around the world that formally support the 1982 call of then Hiroshima Mayor Takeshi Araki for the total elimination of all nuclear weapons. As of May 26, 2005, membership stood at 1,036 cities in 112 countries and regions.