As an advocate for the abolition of nuclear weapons, I don't have the luxury of mincing words. There are an estimated 15,000 nuclear warheads scattered around the world, and eliminating them means speaking truth — and often hard truths — to power. In that spirit, let me be unequivocal: today's leaders are too emotionally unstable to be trusted with the world's nuclear stockpile.

As I told the Nobel committee last year when accepting the Nobel Peace Prize on behalf of my organization, the International Campaign to Abolish Nuclear Weapons, nuclear arms are a "madman's gun held permanently to our temple." And it is mad men with their fingers on the trigger.

For reasons that I cannot fathom, nuclear weapons have been coopted as symbols of male power. In recent months, North Korean dictator Kim Jong Un and U.S. President Donald Trump have publicly bragged about the "size" of their buttons and the robustness of their arsenals.