As we mark the 70th anniversary of the nuclear attacks on Hiroshima and Nagasaki, I am reminded of my visit to those cities five years ago. That moving experience was rendered even more meaningful by my meetings with the hibakusha. The courage and fortitude of these brave survivors was deeply inspiring. I salute their seven decades of principled advocacy for a world free of nuclear weapons.

As the average age of the hibakusha passes 80, I feel a greater sense of urgency to spread their message of peace, which has reverberated from the cities of Hiroshima and Nagasaki to every corner of the world.

Thanks in part to their tireless and outspoken activism, we have achieved great unanimity behind the goal of a world free of nuclear weapons. This would have obvious benefits for all countries and peoples – but despite the clear imperative of nuclear disarmament, there remain serious disagreements about how to achieve it.

That is why I am calling on leaders to stop squandering precious resources on destabilizing weapons and instead embrace a bold and global vision that meets the demands of humanity. I challenge anyone who doubts the urgency of nuclear disarmament to listen to the stories of the hibakusha. No one could look into the eyes of these brave and resilient individuals and claim to know better what nuclear weapons bring.

There is no more fitting occasion to remember the human consequences of nuclear weapons than this solemn 70th anniversary of the bombings of Hiroshima and Nagasaki.

It is also an opportunity to take concrete actions to rid the world of these most destructive weapons. I have long proposed that all parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), particularly the nuclear-weapon-states, fulfil their obligation to undertake negotiations on effective measures leading to nuclear disarmament. They could pursue this goal by agreement on a framework of separate, mutually reinforcing instruments – or consider negotiating a nuclear-weapons convention backed by a strong system of verification.

I have also consistently advocated universal ratification of the Comprehensive Nuclear Test-Ban Treaty, which bans all nuclear tests, constrains the development and proliferation of nuclear weapons, and contributes to progress on nuclear disarmament while helping to protect our environment against the harmful radioactive by-products of nuclear tests.

As an international community, we should seize this moment in history to bridge our divides, find common ground and achieve real progress on disarmament.

We owe it to the hibakusha, all living beings and future generations to mark the 70th anniversary of the bombings and the founding of the United Nations by re-dedicating ourselves to realizing the vision of a nuclear-weapon-free world.