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The changing nature of the Security Treaty: Japan insists on U.S. nuclear umbrella

By Naotaka Fujita and Takateru Doi, senior staff writers, and Taketsugu Sato, senior national security correspondent


Americans are safe from attack because their enemies fear nuclear retaliation. The U.S. is also protecting Japan with extended nuclear deterrence, often called the “nuclear umbrella.” This traditional picture of the Japan-U.S. Alliance is transforming.


On February 25, 2009, the U.S. Congressional Commission on U.S. Strategic Posture held a meeting chaired by former Defense Secretary William Perry. It was a month after the inauguration of President Obama, who had proclaimed support for “a nuclear-free world.” Then-Japanese Political Minister to the U.S. Tsuneo Akiba (current Vice Foreign Minister) was invited to this meeting along with others, where he distributed a three-page memo detailing Japan’s requests to the new administration concerning the U.S. nuclear policy.


Akiba’s memo stated that the security environment surrounding Japan required deterrence measures including the U.S. nuclear arsenal and read, “The United States’ possible unilateral reduction of its operationally deployed strategic nuclear warheads may have an adverse effect on Japan’s security.”


Although it was a closed-door meeting, a document obtained later by an American NGO, the Union of Concerned Scientists, revealed that the Japanese at the meeting had emphasized the importance of the “nuclear umbrella” and urged the U.S. not to reduce its nuclear capabilities unilaterally.


Akiba and his team pointed to “deep and hardened underground facilities, movable targets, cyberattacks, anti-satellite attacks and anti-access/area denial capabilities” as possible threats and urged the U.S. to maintain attack capabilities to counter them. It was clear that the Japanese had China’s rapid military expansion and North Korea’s nuclear development in mind.


The document also testified to Japan’s attempt to preempt a unilateral, large-scale reduction of the strategic warheads deployed by the U.S., arguing that it is crucial for the two countries to discuss such plans in depth prior to any U.S. decision. Japan had been deeply concerned about the Obama administration’s policy, and wanted a platform where it could make a clear case for the indispensability of the nuclear umbrella. 


The U.S. listened to Japan’s concerns. Since 2010, Japan and the U.S. have convened Extended Deterrence Dialogue meetings once or twice a year on a regular basis. A former senior Japanese government official recalls, “We had to have a place where we could make requests to the U.S. on how they utilize their nuclear capacity.”


The Japan-U.S. Security Treaty has always been at the core of the two countries’ alliance relationship. Sixty years ago, when the revised Japan-U.S. Security Alliance was put in force, Japanese demonstrators surrounded the National Diet Building en masse, voicing concern that Japan would be involved in U.S. wars. A senior defense ministry official says, “Today, the issue is how Japan can involve the U.S.”


But this kind of thinking contradicts the Japanese government’s long-standing position to strongly support nuclear disarmament as the sole victim of the atomic bombs.


The Non-proliferation of Nuclear Weapons Treaty in 2017 banned not only possessing nuclear weapons but also using them to threaten others. The Japanese government didn’t even join the 2017 negotiations despite the fact that atomic-bomb victims had urged the government to adopt the treaty. A government official reveals, “If we had agreed with the initiative, the U.S. wouldn’t have been happy.”


Meanwhile, nuclear threats are reemerging in Asia.


In August 2019, the U.S.-Russia Intermediate-range Nuclear Forces Treaty (INF) expired, and the other U.S.- Russia arms reduction framework, the New Strategic Arms Reduction Treaty (New START), is scheduled to expire in February 2021. In a teleconference on April 17, Secretary of State Mike Pompeo stressed to Russian Foreign Minister Sergey Lavrov that any future negotiations over disarmament should be held under a trilateral arms control agreement that includes China. However, China has shown no interest, making the fate of the new START extremely precarious.


As the security environment in Asia deteriorates, Japan’ dependence on the U.S. nuclear umbrella grows, despite its history and the role it should be playing to lead the nuclear-disarmament and non-proliferation efforts. The dilemma for Japan only deepens.


If Japan wants to shelter under the U.S. nuclear umbrella, what is the country prepared to do?


Compared with the North Atlantic Treaty Organization (NATO), the U.S. alliance with Japan is different in that NATO has a ground nuclear arsenal and Japan doesn’t. Is Japan considering changing its policy?


Those were the questions Akiba’s team faced during the Congressional Commission meeting in 2009. According to people who attended, many difficult questions were asked about Japan’s three non-nuclear principles, namely about “not to allow their entry into Japan.” The Japanese answered that although it was inconceivable to change the non-nuclear principles, Japan had been acutely aware of the threats.


It was obvious that not doing anything wasn’t an option for Japan. The 2009 memo that the Japanese team presented to the meeting clearly stated that the deterrence is to be achieved through cooperation between the two countries and expressed Japan’s willingness to contribute to the deterrence against enemy attacks, suggesting Japan’s intention to enhance its defense capabilities, including conventional weapons.


So, ever since 2010, Japan’s defense policy has been formulated on the premise that Japan contributes to the deterrence of the Japan-U.S. Alliance through enhanced conventional defense capabilities, while regularly confirming the U.S. commitment to the nuclear umbrella.


In 2010, the National Defense Program Outline called the U.S. nuclear umbrella indispensable and emphasized the importance of increasing Japan’s role by enhancing ballistic missile defense and other capabilities.


In 2013, the national security strategy introduced the expression “the deterrence of the Japan-U.S. Alliance.” Traditionally, the word “deterrence” meant the defense of Japan by the U.S. military. “With China and North Korea in mind, Japan presented a new posture in which it takes part in the deterrence.” (A senior defense official)


Then in 2014 the Abe administration approved the reinterpretation of the Constitution with regard to the right to collective self-defense. This opened the way to the enactment in 2015 of the security laws that enabled the Japanese Self-Defense Forces to protect U.S. military vessels in peacetime and during “grey-zone conflicts,” contingencies that don’t involve  armed conflict. A senior defense official who had taken part in the formulation of the security laws said, “Increasing Japan’s contribution to conventional defense will increase the security the nuclear umbrella provides.”


These days, Japan relies on a joint statement of February, 2017, as proof of the U.S. commitment. It was issued after the first meeting between Prime Minister Shinzo Abe and the newly inaugurated President Trump, who had been voicing his opinion that the U.S. could no longer be the world’s policeman.


The statement emphasized: “The U.S. commitment to defend Japan through the full range of U.S. military capabilities, both nuclear and conventional, is unwavering.” This was only the second time, after 1975, that the word “nuclear” was used in a joint document issued by the leaders of the two countries in the context of the defense of Japan.


This statement in 2017 was drafted by Japanese officials, who had been wary of the first steps the new president might take. A senior foreign ministry official said, “We needed to secure the ‘nuclear umbrella’ at the earliest opportunity after the new administration launched.”


Japan-U.S. cooperation has deepened at the operational level. In 2017, the Maritime Self-Defense Force and three U.S. Navy vessels, including a nuclear-powered aircraft carrier, conducted a joint exercise in the Sea of Japan. The exercise aimed at deterring North Korea, which was repeatedly launching ballistic missiles. A government official explains, “The deterrence of the Japan-U.S. Alliance is a multi-layered plan, starting from peacetime preparedness to the U.S. nuclear capability at the top.” 


Masashi Murano, a researcher at Hudson Institute, agrees. “In order to enhance the deterrence capability of Japan and the U.S.,” he said, “We need to boost our operational planning capabilities simultaneously.”


In January 2020, Prime Minister Abe responded to questions in the Diet about the security law, which divided the nation, saying, “It enables the alliance partners to protect each other and further strengthens the ties between the two countries.”


Signs of a nuclear race in Asia and the dilemma of the A-bombed nation


During the Cold War, nuclear deterrence had worked to a certain extent, preventing the U.S. and the USSR from employing their nuclear arsenals. However, now that the main nuclear theater has moved to Asia, the bar for the use of nuclear weapons has lowered and as a result, there is increasing uncertainty.


Unlike the Obama administration, the Trump administration is in pursuit of a greater nuclear capability. In the 2018 Nuclear Posture Review (NPR), revised for the first time in eight years, China and Russia were cast as U.S. adversaries. In a reversal of past policy that had limited the use of nuclear weapons to a response to an enemy nuclear attack, the new NPR indicated the possibility of a nuclear response to non-nuclear attacks.


Also keeping pace with Russia, the U.S. is now moving to develop and deploy low-yield nuclear weapons that are supposed to cause less damage and help avoid full-scale nuclear war. However, some point out those small nuclear weapons actually lower the hurdle for nuclear attacks as well.


According to Gregory Kulacki of the Union of Concerned Scientists, President Trump’s NPR discusses the future role of US nuclear options in Asia in a way that is much more in line with the preferences in the 2009 statement of Akiba and the Japanese government. Kulacki pointed out that the nations should have learned during the Cold War that nuclear dependency incites mutual distrust and leads to an arms race. He stressed that Japan should instead lead a trilateral discussion on arms control with the U.S. and China.


Currently, no framework exists in Asia to control nuclear arms. In February 2020, the U.S. announced that it had equipped submarine-launched ballistic missiles (SLBM) with small nuclear warheads. Although China possesses fewer nuclear warheads than the U.S., it has been building up its nuclear capability and is the sole Nuclear Non-Proliferation Treaty (NPT) signatory that is increasing its number of warheads.


Meanwhile, in 2013, Japan declared in the National Security Strategy: “Japan, as the only country in the world to have suffered atomic bombing in war, will continue its vigorous efforts to seek ‘a world free of nuclear weapons’.” What should be Japan’s role in preventing a nuclear war? Its dilemma continues.


The question remains: is the Japanese government capable of leading an effort to prepare a framework for arms control in Asia to counter the growing nuclear threats in the region?

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