The 2026 Japan-U.S. Base Agreement Renegotiation Indicates a Structural Transformation of the Alliance

On January 27, I felt a strong sense of discomfort during an 18-minute speech given by U.S. Deputy Secretary of Defense Elbridge Colby in Seoul. The word "China" appeared seven times, while there was no mention of "North Korea" at all. There was not a single word about the reason for the presence of 28,000 U.S. troops in South Korea, which is the defense of the Korean Peninsula.

This speech is not merely a diplomatic consideration. It embodies the fundamental redefinition of Northeast Asian security indicated by the National Security Strategy (NSS) and the National Defense Strategy (NDS) announced by the Trump administration at the end of last year. The renegotiation of the Special Measures Agreement (SMA) between Japan and the U.S., which will expire in 2026, will serve as a litmus test for what this structural transformation will bring to Japan.

From "Cost Sharing" to "Strategic Division of Labor"

Under the current SMA, Japan bears approximately $1.9 billion (about 280 billion yen) annually, covering part of the utility costs of U.S. military bases, salaries for base employees, and training relocation expenses. This has been regarded as the most generous host nation support in the world.

However, this negotiation goes beyond mere increases or decreases in amounts. According to an analysis by Military.com, the U.S. side is seeking discussions based on "repositioning." This does not mean withdrawal, but rather a "distributed deployment" that involves relocating some Marines from Okinawa to Guam or Australia and enhancing the capabilities of Kadena Air Base and Yokosuka Naval Base.

The problem is that the purpose of this distributed deployment is shifting from Japan's defense to deterrence against China across the entire First Island Chain. The NDS clearly states, "South Korea has the capability to take primary responsibility for deterring North Korea with more limited support from the United States." This logic naturally applies to Japan as well.

What the 2% GDP Defense Spending Means

The Japanese government plans to raise defense spending to 2% of GDP by fiscal year 2027. This represents a historic shift since the end of the Cold War. However, U.S. expectations are not merely for a budget increase.

The NSS calls on allies to "increase spending on the capabilities necessary for the defense of the First Island Chain, particularly new capabilities." This means acquiring retaliatory capabilities such as extending the range of the Type 12 surface-to-ship guided missile and Aegis-equipped ships. This signifies an expansion of roles from defending national territory to broader deterrence, including contingencies in Taiwan.

From my experience working in Yokosuka for 25 years, the Japan Maritime Self-Defense Force's escort fleet is already facing personnel shortages and maintenance burdens. The expansion of new missions could place considerable strain on the field.

The Political Cost of the Futenma Issue

Inextricably linked to the SMA negotiations is the nearly 30-year unresolved issue of relocating Futenma Air Station. The relocation to Henoko has been stalled due to strong local opposition and lawsuits.

For the U.S., this delay is not merely an infrastructure issue. It raises doubts about Japan's political decision-making capacity. The distributed deployment strategy assumes a rapid reorganization of base functions. However, the example of Futenma shows the reality that consensus-building within Japan can take a decade or more.

Okinawa accounts for only 0.6% of Japan's land area but hosts about 70% of U.S. military facilities in Japan. If new role expansions are sought without addressing this imbalance, backlash from the host communities is inevitable.

Overlooked Fundamental Risks

According to reports from Asia Times, the Trump administration removed the phrase "denuclearization of North Korea" from the NSS. Furthermore, there is no mention of a military alliance between North Korea and Russia. This is seen as a tactical consideration to seek a reconvening of talks with Kim Jong-un, but I interpret it differently.

The U.S. is increasingly centralizing its threat perception in Northeast Asia around "balancing against China." It seems to be attempting to geographically separate threats, treating North Korea's nuclear missiles as a South Korean issue and the Taiwan Strait as a U.S.-Japan-Australia issue.

However, for Japan, which faces North Korea across the Sea of Japan, the threat from North Korea is by no means just a "South Korean issue." The flight time of ballistic missiles is under 10 minutes, and there have already been multiple landings in the EEZ off the Noto Peninsula. If the U.S. views this threat as a subject of "limited support," the credibility of extended deterrence will be fundamentally undermined.

Questioning the Asymmetry of the Alliance

What Japan faces in the 2026 SMA negotiations is not a negotiation over amounts. It is the fundamental question of "Why are U.S. forces in Japan?"

Even if Japan increases its defense spending, acquires retaliatory capabilities, and contributes to the defense of the First Island Chain, there is no guarantee that it will protect its citizens from North Korea's nuclear missiles. Conversely, deepening involvement in a Taiwan contingency increases the risk that Japan itself will become a target.

The real issue is not the amount of the SMA or the configuration of bases. It is whether the strategic objectives of Japan and the U.S. are aligned, a verification that has been postponed. If the discussion remains focused solely on cost-sharing, this fundamental rift will remain concealed. The silence of Deputy Secretary Colby in Seoul regarding North Korea is the most eloquent signal for the future of the alliance.