Tokyo: When Terumi Tanaka, 85, declares that nuclear weapons simply cannot coexist with humanity, he speaks with conviction.
"I saw with my own eyes the inhumanity and the cruelty of these weapons," says Tanaka, who was 13 when the A-bomb hit Nagasaki in Japan's south-west in the dying days of World War II.
He was in a house 3.2 kilometres from the blast centre and lost five of his family members at once. This searing childhood experience has come to define the rest of his life: "Through this experience I have called on the world to never again drop such weapons upon human beings. They must be removed from the Earth and abolished as quickly as possible."
Disarmament activists hope that the awarding of this year's Nobel Peace Prize to the International Campaign to Abolish Nuclear Weapons (ICAN)??? - a group started in Melbourne??? - ???will help build momentum for change, even as North Korea's drive to develop such bombs makes the prospect of a breakthrough look as distant as ever.
The handful of states that already possess nuclear weapons, including the US and Russia, are in no rush to do away with them, viewing them as a strong deterrent against attacks from other countries. Australia and Japan - which rely on US security guarantees - joined the nuclear weapons states in shunning recent United Nations talks on a legally binding way to ban such weapons, although 122 non-nuclear countries voted in favour of the treaty in New York in July.
For Tanaka and fellow campaigner Suechi Kido, 77, arguments about nuclear disarmament are more than just an academic debate.
"I was five years old when I experienced the nuclear bomb," recalls Kido.
"I was on the street around two kilometres from the hypocentre [in Nagasaki]. Half of my face was badly burnt and the next day as I walked through the centre of the city past the hypocentre I saw a terrible scene. The scenes were burnt into my eyes - ???the fact that the city was completely gone, that there were bodies lying around all around me and there were groups of people asking for water."
Both men are heavily involved in Hidankyo, a Japanese group established in 1956 to represent the survivors of the Hiroshima and Nagasaki bombings. By the end of 1945 the number of estimated deaths had risen to 140,000 and 74,000 respectively. The remaining hibakusha, or atomic bomb victims, have been fighting to "save humanity from the same fate" that those cities experienced. They say they are "embarrassed and angry" that their country??? - ???the only one to have suffered a nuclear attack - ???has opted not to join the ban treaty.
Now, for reasons other than the devastation of 1945, Japan has cause to be heavily engaged in the nuclear weapons debate. North Korean leader Kim Jong-un's regime has test-fired several ballistic missiles over the country in the past couple of months. Residents in the northern prefecture of Hokkaido have been woken twice by early-morning emergency alerts warning that a missile was about to pass over their region.
Japanese Prime Minister Shinzo Abe has seen his political stocks recover from the scandal-fuelled lows of July as he insisted on taking a firm line against North Korea. Abe, who called a snap lower-house election for this Sunday, says now is the time for pressure, not dialogue.
While Abe won't comment on the appropriateness of Donald Trump's brash rhetoric - which has included threats of "fire and fury like the world has never seen" - the Japanese leader supports the US President's position that all options, including military ones, should remain on the table.
"North Korea is attempting to dismiss with a smirk the efforts towards disarmament we have assiduously undertaken over the years," Abe told the UN General Assembly last month. "The non-proliferation regime is about to suffer a serious blow from its most confident disrupter ever."
While North Korea insists its development of a nuclear arsenal is an insurance policy against a US-led invasion aimed at regime change, Pyongyang could resort to "the unthinkable" if it believed it was about to be attacked.
As many as 2.1 million people could die and 7.7 million more could be injured if North Korea detonated multiple nuclear weapons over Tokyo and Seoul, according to one recent estimate. These figures, based on the regime's current estimated weapon yields, were published by 38 North, the respected analytical service run by Johns Hopkins University in the US.
Japan is upgrading its missile defence systems amid growing fears about the danger posed by North Korea. At the same time, Abe's Liberal Democratic Party is looking to bolster the status of the "self-defence forces" in Japan's constitution, which was not been amended since the country renounced war after the World War II surrender.
While there is no suggestion Japan is about to go down the path of developing its own nuclear weapons, some politicians are publicly discussing the possibility.
The developments are frustrating for disarmament campaigners. Kido says he is sad to see that the current political environment is inflaming the North Korea issue and that there is no apparent movement towards dialogue.
For Akira Kawasaki, a member of the ICAN international steering group and of the Peace Boat executive committee, the security debate is too narrowly focused.
"States surrounding North Korea are always talking about disarming North Korea; that North Korea is a bad country so we need to disarm," Kawasaki said during a presentation to the Foreign Correspondents' Club of Japan.
"But the real issue is that nuclear weapons are bad weapons. We need to eliminate the bad weapons and there's no right hand on wrong weapons."
Kawasaki says he is lobbying Japanese politicians to properly debate the broader issue of nuclear disarmament during the election campaign. He thinks that the Nobel committee's decision to highlight the nuclear ban treaty is an attempt to nudge the world towards a "real solution".
Signatories to the Treaty on the Prohibition of Nuclear Weapons commit not to possess, stockpile, use or threaten to use such weapons. States that already have such weapons would be required to reach safeguards agreements with the International Atomic Energy Agency and cooperate with authorities to verify the irreversible elimination of their nuclear programs.
The Australian government argues such a treaty "would not rid us of a single nuclear weapon" without the participation of the key nuclear states. Like Japan, Australia sees the existing non-proliferation treaty as the cornerstone of disarmament efforts.
Kido says it's now even more important that his message is heard by government and citizens around the world. This is because the number of people who can share their direct experience of the horrors of nuclear weapons is dwindling.
"The number of hibakusha currently alive is around 160,000 people, but the average age is 81 years and so there's not much time left to meet directly with these hibakusha," Kido says. "I would like to request all of you to listen to our story."
Asked how the hibakusha maintain hope when the prospects of disarmament seem so distant, Tanaka replies: "My principle is that nuclear weapons must never be used; they are a form of weapon that cannot coexist with humanity. And this conviction is something that has given me strength and I have been working to bring that to a reality. It's actually been my life's work."
Tanaka says that the fact that the nuclear weapons states are not participating in the prohibition treaty "just motivates me to raise my voice even louder to call for the abolition of these terrible weapons".
