On August 6, 1945, a US B-29 bomber dropped the first-ever atomic bomb over the Japanese city of Hiroshima.

At least 140,000 people were killed in the attack and tens of thousands more died later because of the effects of radiation.

Ever since the end of the World War II, there's been an international consensus and effort to contain the spread of nuclear weapons. The global community has created several organisations and signed treaties to prevent potential nuclear attacks.

"I think today, we are now facing the same situation as if we were the day after the bombing of Nagasaki and Hiroshima, because today, still the most crucial political, moral and social challenge is how to stop nuclear explosion from happening on this planet again," the Executive Secretary of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) Lassina Zerbo tells Al Jazeera.

As of today, nine countries have admitted to possessing nuclear weapons. But only five - the US, Russia, the UK, France and China - are part of the 1968 Nuclear Non-Proliferation Treaty, which calls on its signatories to open their doors for inspection by the International Atomic Energy Agency (IAEA).

The IAEA is one of the organisations promoting the peaceful use of nuclear technology - while a 1996 treaty, the Comprehensive Nuclear Test Ban Treaty banned all nuclear tests for civilian and military purposes.

But there are 12 states which have neither signed nor ratified that treaty. Among them are three with nuclear weapons: North Korea, India, and Pakistan.

With North Korea launching missiles and the growing conflict between India and Pakistan, can the world prevent a nuclear attack?

"When I hear the word 'pushing the button', it frightens me. My biggest hope is that when we get close to any catastrophe, we come to our sense somehow," says Zerbo. "I think I see no way in this civilised world, no way in this 21st century any decent government or decent political leader thinking about pushing the button of the nuclear weapon because they know how devastating that could be. Because it's not a war that anyone can win. It's for all of us to lose."

The Executive Secretary of the Comprehensive Nuclear Test Ban Treaty Organization Lassina Zerbo talks to Al Jazeera about North Korea, the collapsing Iran nuclear deal, Saudi Arabia's nuclear programme, India-Pakistan tensions, a new nuclear arms race, and the global threat of nuclear war.

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