In a speech on Sept. 6, US Special Representative for North Korea Stephen Pigeon warned that Japan might respond to the growing nuclear threat from Pyongyang by developing its own nuclear weapons. Japan has long had the means to acquire nuclear weapons thanks to its advanced nuclear power industry. But since a security treaty was approved in 1951, Tokyo has relied on Washington's "extended deterrence" - a promise that any attack on Japan would provoke retaliation from the United States. The Japanese government's confidence in this commitment has fluctuated over the past half-century, and Pigeon is not the first US official to fear that Tokyo will lose faith.

On three occasions, over the past 50 years, Japan has considered the advantages and disadvantages of developing nuclear weapons. The first sensitive moment in the 1960s came after China began its nuclear tests. Then during the 1990s after the Cold War, Japanese officials worried that Washington might feel less determined to defend Japan against Russian nuclear power. Recently, Japan faced a major new challenge from its western neighbor, after North Korea developed nuclear weapons in 2006. But at every turn, Japanese security experts have concluded that it makes more sense to rely on expanded deterrence provided by the United States. In return, Japan presented itself to US policymakers as a key element of peace and stability in Northeast Asia, a regional center for the deployment of US troops and military equipment (as was the case during the Korean and Vietnam wars), and a bulwark against China.

Guarantee is reliable

Today, the US warranty for security seems less reliable. This summer, President Donald Trump has repeatedly described the security pact as unfair, and is said to have rejoiced in private to cancel the treaty altogether. He allowed tests of Korean missiles despite threatening Japan. During his election campaign, he said: Japan and South Korea's development of nuclear weapons could serve the interests of both countries. There are still strong historical, cultural and institutional reasons for Japan to resist turning to nuclear weapons, but Pigeon is right to worry that the country may be heading in that direction - even though it is the US president, like North Korea, that could push Tokyo toward nuclear proliferation.

Most prominent supporters

As the only country to have been bombed, Japan is a key supporter of nuclear non-proliferation. But it is quietly pursuing a strategy of "nuclear reserve" and maintaining the ability to develop nuclear weapons without intending to do so. Officials sometimes reveal the existence of this policy. In the aftermath of the Fukushima nuclear disaster in 2011, for example, former defense minister Shigeru Ishiba, a senior LDP politician, explained that Japan could not shut down nuclear power plants because of the nuclear fuel cycle. - Industrial processes that convert uranium into electricity and waste recycling - were necessary to maintain "technical deterrence." Japan is the only country with the capability to enrich uranium and reprocess plutonium, but has no nuclear weapons.

In theory, Japan could develop a small atomic arsenal in less than a year or two. You will need to produce weapons-grade plutonium, a process that is likely to require the installation of civilian reactors. You will also need to re-engineer advanced launch missiles suitable for nuclear warheads. Japanese scientists are technically capable of both tasks and can accomplish them in a tight schedule if the government feels compelled to reduce concerns about safety, confidentiality, reliability and accuracy.

However, scientists will face another obstacle in finding a place to test weapons in the crowded Japanese archipelago. The latest government study, conducted in 2006, concluded that Japan had the technical expertise and facilities to develop a small nuclear warhead, but it would take three to five years to do so and cost more than $ 2 billion.

3 Principles

The biggest obstacles to Japan's nuclear weapons program are not technical or logistical; they are political, legal and cultural. Since 1972, following the restoration of Okinawa from the United States and the removal of nuclear weapons stationed there, Japan's prime ministers have adopted "three non-nuclear principles" as a morally and politically binding rule: no industry, no possession and no reception of nuclear weapons controlled by other countries. In practice, the third principle of allowing nuclear-armed US ships to dock at ports was violated. In addition, Japan's support for the Nuclear Non-Proliferation Treaty (NPT), the Comprehensive Nuclear-Test-Ban Treaty (CTBT) and other non-proliferation clauses reinforces political constraints on nuclear weapons possession, as well as the collective memory of the bombing of Hiroshima and Nagasaki. Japanese Prime Minister Shinzo Abe shows no sign of seeking to challenge this trend.

Opposition to nuclear weapons is particularly strong in academia and science, including in the field of nuclear technology. In addition to having a strong atomic energy watchdog in Japan, a culture of deep-seated hostility to nuclear weapons will make it almost impossible for Japan to take a secret path to the bomb.

Japanese diplomats are also concerned about the security costs of nuclear weapons. Any domestic nuclear program would be provocative to China, leading to a new acceleration in Beijing's increase in nuclear and conventional weapons. Developing nuclear weapons would increase the risk of a pre-emptive nuclear strike from North Korea and provoke South Korea to acquire its nuclear arsenal, fueling regional tensions.

The last option

The scientific establishment is only likely to comply with nuclear weapons, in the event of a sharp deterioration in the security situation in Japan. In Japanese policymakers' perceptions, the most likely scenario is for South Korea to become nuclear, or if the two Koreas unite and maintain Pyongyang's current arsenal. Japanese officials watched with interest as South Korean President Moon Jae-in expressed appreciation for the merits of unification with North Korea in a speech on Aug. 15 to celebrate liberation from Japan.

While Moon insisted that a united Korea would not retain nuclear weapons, Japan remained cautious in light of pro-nuclear sentiment on both sides of the Korean peninsula. Unlike South Korea, where politicians and columnists in major newspapers are demanding a domestic nuclear weapons program, advocates of the right to nuclear weapons in Japan are far-right.

After North Korea's first nuclear test in 2006, for example, Foreign Minister Taro Aso called for a public debate on the circumstances that warrant a serious review of Japan's non-nuclear policy.

Of course, Tokyo's position on nuclear weapons is shaped primarily by its belief in the credibility of US nuclear deterrence. Over the years, this credibility has come into question when the United States lost the Vietnam War, withdrew from the Philippines, failed to prevent China, and then North Korea to acquire nuclear weapons, and reduced its nuclear arsenal.

Security commitment

President Donald Trump has done more than any of his predecessors to undermine the credibility of US nuclear deterrence. In what appeared to be a blatant disregard for Japan's security interests, he argued with Shinzo Abe at the G7 summit in April this year whether North Korea's missile launches violated UN resolutions. Although the presence of US troops in Japan provides some reassurance, Trump's "America First" ideology is an additional reason for Japan to keep its nuclear options under consideration.

Any Japanese move to develop nuclear weapons must be seen as a cry for help. In the past, when Japanese leaders signaled to Washington that they were considering nuclear weapons, their goal was to encourage a stronger US security commitment to their country. The call for a public debate in 2006 sparked a new confirmation of this commitment from Secretary of State Condoleezza Rice. In 1964, Prime Minister Isako Sato raised the prospect of nuclear weapons to persuade President Lyndon Johnson to strengthen Washington's pledge to protect Japanese security. Washington should learn from that history and allay Japan's fears, starting with clear Trump statements reassuring Tokyo, refusing to succumb to North Korean provocations, and discouraging nuclear proliferation in an already tense region.

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