Japan's Defense Policy Faces a Historic Turning Point: Lifting of Arms Export Ban, Joint Construction of U.S. Navy Vessels, and the New Security Environment in Northeast Asia

From late April to early May 2026, movements surrounding Japan's security policy are rapidly accelerating. Prime Minister Sanae Takaichi is leading a fundamental revision of the three principles of defense equipment transfer, the U.S. Department of Defense is considering outsourcing shipbuilding to Japan and South Korea, and China has issued warnings at the United Nations regarding Japan's potential for a "nuclear breakout." These three developments indicate that the post-war Japanese security system is being fundamentally restructured, not just limited to individual policy changes.

On April 21, Prime Minister Takaichi decided to revise the three principles of defense equipment transfer and their operational guidelines in a cabinet meeting. Established in 2014, this system has regulated the overseas transfer of Japan's military hardware and technology, but the recent revision effectively allows the export of all types of defense equipment, including lethal weapons. Previously, the overseas transfer of Japanese military equipment was limited to non-lethal systems in five categories, but this restriction has been lifted. On the same day, Prime Minister Takaichi stated on social media, "As the security environment becomes increasingly severe, no country can protect its own peace and security alone, and it is necessary to have partner countries that mutually support each other in terms of defense equipment," emphasizing the legitimacy of the revision.

This decision is a clear deviation from the principle of banning the overseas sale of lethal weapons, which has been maintained for decades under Japan's post-war pacifist constitution. According to data from the Stockholm International Peace Research Institute (SIPRI), despite its technological capabilities, Japan's share of global arms exports remains extremely small, contrasting sharply with the current situation where both China and South Korea are among the world's top 10 arms-exporting countries. Analysts point out that this revision opens the door to the export of high-end defense platforms, including sixth-generation fighter jets. The impact of this system change on the future of the next-generation fighter program (Global Combat Air Program, GCAP) that Japan is co-developing with the UK and Italy is considered to be significant.

In a move that seems to support the international evaluation of Japan's defense industrial base, it has become clear that the U.S. Department of Defense has begun considering outsourcing the design and construction of warships to Japanese and South Korean shipyards. According to a report by USNI News, the 2027 budget includes $1.85 billion for a feasibility study, which will investigate the possibility of adopting or jointly producing Japan's Mogami-class frigate and South Korea's Daegu-class frigate. The Mogami-class features a 5,500-ton stealth hull and advanced automation, while the Daegu-class, at 3,600 tons, is equipped with a quiet propulsion system. Both ships are important for their incorporation of U.S. standard systems such as the MK-41 vertical launch system.

If this plan is realized, it would mark the first time since World War II that the U.S. procures major surface combatants from foreign partners. The background to this is the chronic delays, labor shortages, and cost overruns faced by the U.S. shipbuilding industry, which have led to dissatisfaction from the Trump administration. More critically, China is currently building 6 to 10 destroyers annually, which corresponds to 4 to 6 times the U.S. construction rate, highlighting a significant disparity in shipbuilding capabilities. If the feasibility study budget is approved, defense industrial cooperation among Japan, the U.S., and South Korea will reach an unprecedented level in practical terms of arms procurement.

On the other hand, this shift in Japan's defense policy is creating new tensions with China. At the end of April, the Chinese Ministry of Foreign Affairs issued a document ahead of a meeting at the United Nations headquarters, warning that Japan has mastered the ability to extract weapon-grade plutonium and possesses the technology and facilities necessary for reprocessing. The document pointed out that "Japan has produced and holds plutonium materials far exceeding the actual demand for its civilian nuclear program over many years, and has the capability to achieve a nuclear breakout in a short period," calling for it to be made a significant agenda item at the UN. China, as a permanent member of the UN Security Council, will serve as the rotating president in May.

This Chinese move indicates that the security environment in Northeast Asia is becoming increasingly complex and multilayered. On April 26, Russian Defense Minister Sergei Shoigu met with North Korean leader Kim Jong-un in Pyongyang and revealed that preparations are underway to sign a five-year military cooperation plan from 2027 to 2031. Shoigu stated that the relationship between the two countries is at an "unprecedentedly high level," and analysts point out that this cooperation framework, which could accelerate North Korea's military modernization, is also a concern for China.

Data from SIPRI's annual report supports the notion that these individual policy trends are part of a larger structural change. Military spending in the Asia-Pacific region in 2025 increased at the fastest pace in 16 years compared to the previous year, reaching a total of $681 billion. One factor behind this acceleration is that U.S. allies are feeling "increasing uncertainty" about whether Washington will adhere to its security commitments. The influence of the Trump factor on regional defense policies functions as a common variable that permeates the entire Northeast Asian security environment, from Japan's lifting of its arms export ban to expectations for South Korea's shipbuilding industry, and even to the deepening military cooperation between North Korea and Russia.

Global military spending is projected to reach $2.89 trillion in 2025, marking an increase for the 11th consecutive year. The military expenditure as a percentage of GDP has reached 2.5%, the highest level since 2009. The combined spending of the top three countries— the U.S., China, and Russia—amounts to $1.48 trillion, accounting for more than half of the global total. However, the global growth rate for 2025 is slowing to 2.9%, down from 9.7% the previous year, primarily due to a 7.5% decrease in U.S. military spending, as there were no new military aid approvals for Ukraine.

What these series of trends signify is the reality that Japan's long-maintained framework of "defensive defense" is being significantly redefined in substance, while its name is being preserved. The complete lifting of the arms export ban, participation in international co-development and export of high-end defense platforms, and a new role as a partner in U.S. Navy shipbuilding—these are multiple indicators that Japan has begun to earnestly pursue its status as a "normal nation" in terms of security. As discussions about amending the pacifist constitution under the Takaichi administration become a real political issue, the developments in Japan's defense policy over the coming months will likely become a decisive variable in shaping the security architecture across Northeast Asia.