Global Zero leaders call Obama and Medvedev joint statement an historic commitment to eliminating all nuclear weapons worldwide

Warheads no longer keep us safe. Six security experts urge America and Russia to act today

When presidents Barack Obama and Dmitry Medvedev meet today for the first time, they will have an historic opportunity to confront the most urgent security threat to our world: the proliferation of nuclear weapons and the risk of nuclear terrorism. The two leaders can move beyond traditional arms control and, in a bold move, set the world on a course towards the total elimination of all nuclear weapons - global zero.

In London, they should agree that the US and the Russian Federation will begin work immediately to achieve an accord for deep reductions in their arsenals and then lead a longer-term effort with other nuclear powers to eliminate all nuclear weapons worldwide through phased and verified reductions.

Today nine countries have more than 23,000 nuclear weapons, many of which are programmed to launch in minutes. A nuclear conflict - or accident - could cause millions to die in a flash and create an environmental catastrophe that would last for generations.

Terrorist groups have been trying to buy, build or steal nuclear weapons, and in the last two decades there have been at least 25 instances of nuclear explosive materials being lost or stolen. If terrorists were to get their hands on a bomb and explode it in a big city, hundreds of thousands of people would die instantly. More