As the 76th anniversaries of the U.S. atomic bombings of Hiroshima and Nagasaki approach, survivors of the catastrophe are pinning their hopes on Japan joining a U.N. treaty prohibiting nuclear weapons that took effect in January, seeing it as a key step in realizing their dream of a nuclear-free world.

But some experts say the goal is unrealistic for Japan as nuclear threats continue to exist in the region while an existing nonproliferation treaty is not working properly amid growing tensions in relations between the United States and fellow nuclear superpowers Russia and China.

The Dongfeng 41, a nuclear-capable intercontinental ballistic missile, is on display during a military parade in Beijing on Oct. 1, 2019, marking the 70th anniversary of the founding of the communist People's Republic of China. (Kyodo) ==Kyodo

Terumi Tanaka, 87, a co-chairperson of the Japan Confederation of A- and H-Bomb Sufferers Organizations, insists that Japan, the only country to have experienced nuclear attacks, should approve the treaty signed by 86 countries, criticizing the government for making "a foolish choice" not to join it.

Protected by the U.S. nuclear umbrella against security threats, in particular from North Korea and China, Japan, along with nuclear-armed states, has stayed away from the U.N. Treaty on the Prohibition of Nuclear Weapons, or TPNW, which bans the development, testing, possession and use of nuclear arsenals.

Although the Nuclear Non-Proliferation Treaty, joined by over 190 countries, serves as a broader platform, the new treaty and the NPT would be "mutually complementary," said Tanaka, who survived the atomic bombing of Nagasaki on Aug. 9, 1945.

The NPT, which took effect in 1970, while aimed at preventing the spread of nuclear weapons and related technology and achieving nuclear disarmament, allows the five permanent members of the U.N. Security Council, all nuclear powers, to possess nuclear arsenals.

Terumi Tanaka, a co-chairperson of the Japan Confederation of A- and H-Bomb Sufferers Organizations, speaks during the opening of the A-bomb exhibition at the U.N. headquarters in 2015 in New York, where a conference was held to review the Nuclear Non-Proliferation Treaty. (Photo courtesy of Nihon Hidankyo)(Kyodo)

Tanaka said Japan should withdraw from its defense alliance with the United States and its nuclear umbrella in order "to be neutral."

Akira Kawasaki, a campaigner of the International Campaign to Abolish Nuclear Weapons, which won the Nobel Peace Prize in 2017 for its efforts that led to the adoption of the nuclear ban treaty, says Japan should at least join as an observer.

"A move toward nuclear disarmament is gathering steam after the nuclear ban treaty came into effect," Kawasaki told a press conference in early July.

But their calls come as discussions on nuclear disarmament remain moribund with the United States, China and Russia expanding their nuclear capabilities in a "new cold war." The next NPT review conference, meanwhile, has been postponed due to the coronavirus pandemic.

A security expert who supports nuclear disarmament and one who advocates the opposite position of maintaining nuclear deterrence both say there are no benefits for Japan in joining the new treaty. They also call for Japan to continue to rely on the U.S. nuclear umbrella and enhance its defense capabilities.

Photo shows Nobumasa Akiyama, a professor of international politics at Hitotsubashi University. (Photo courtesy of Nobumasa Akiyama)(Kyodo)

Nobumasa Akiyama, a professor of international politics at Hitotsubashi University and advocate of nuclear disarmament, pointed to the possibility of some countries leaving the NPT thinking that the new treaty would be more effective in leading to disarmament.

Moreover, as Japan is a "stakeholder in the security dynamic in East Asia," if it joins the TPNW, it would lose its diplomatic leverage and leave its security "in the hands of China" as the Asian giant becomes increasingly assertive militarily, especially in the East and South China seas, Akiyama said.

"It does not necessarily have to be TPNW to reduce nuclear arms," said Akiyama, although he did hold out the possibility that the postponement of the NPT review conference could buy time for further thought on how to reconcile the two treaties.

Sugio Takahashi, head of the Defense Policy Division at the National Institute for Defense Studies, said the new treaty is likely to deepen the rift between what he called an "idealistic nuclear disarmament group" and a "realistic nuclear risk reduction group."

"By creating the TPNW, it made things more complicated as the NPT is not working properly now," said Takahashi, who backs nuclear deterrence.

In explaining why Japan has not joined the new treaty, Japanese Prime Minister Yoshihide Suga told parliament in January, "It is not supported not only by nuclear-weapon states but also by many non-nuclear-weapon states."

Instead, he said, Japan should work to build bridges between countries with different positions by submitting resolutions calling for nuclear disarmament at the United Nations and making efforts to convey the reality of the suffering an atomic bombing causes.

But Japan's assertiveness in calling for nuclear disarmament has been limited as it and other like-minded countries grow wary of China's rapid expansion and modernization of its nuclear arsenal.

Photo shows Sugio Takahashi, the head of the Defense Policy Division at the National Institute for Defense Studies, during an interview with Kyodo News in Tokyo on July 17, 2021. (Kyodo)

Rather than joining the TPNW, the U.S. administration of President Joe Biden is seeking to promote efforts to reduce nuclear weapons stockpiles with Russia as well as China, but Beijing has resisted, Robert Wood, the U.S. disarmament ambassador, told a U.N. conference in May.

Takahashi, however, warned that an "arms race spiral" could occur among the United States, Russia and China if they collaborate "triangularly or make a rough parity treaty," since each one of the three might later become concerned about the other two forming an alliance against it and seek parity with their combined arsenals.

"We would never be able to abolish nuclear weapons if that happens," he said. "It is necessary to relax tensions while maintaining strategic stability."

At a time when talks between nuclear and non-nuclear states are running out of steam, Akiyama said Japan should create a forum to bring together international experts on nuclear strategy both from nuclear powers as well as countries calling for the abolition of nuclear weapons.

"In the dialogue they would need to discuss strategic elements, including new ways for arms control, with the reduction of nuclear weapons and their role as one of the main goals," he said.

A launch test of a Minuteman 3 intercontinental ballistic missile, capable of carrying nuclear warheads, is conducted at a U.S. base in California in May 2017. (Photo courtesy of the U.S. Air Force)(Kyodo)