TOKYO - The emergence of U.S. President Donald Trump's first administration suggested the arrival of a new Cold War era characterized by "great power competition." However, just a decade later, the prospect of a new Cold War, with the democratic camp confronting a new "axis of evil" composed of China, Russia, Iran and North Korea, has quickly faded.
The launch of the second Trump administration brought about what U.S. political scientist Stacie Goddard calls "great power collusion," in which "might makes right" is pushed to the forefront and deals with China and Russia are pursued.
Amid the resurgence of great power politics, alliances with the United States have lost their place. Ever since the United States declared that it is "not the world's policeman," it may have been necessary to anticipate that asymmetrical alliances with the United States would become targets of "great power collusion."
The collapse of the postwar liberal international order and the resurgence of great power politics have caused alliances to shift from frameworks for international cooperation based on shared values and principles to instruments reminiscent of 18th- and 19th-century-style balance-of-power politics among major powers.
For the Trump administration, only major powers capable of influencing the balance of power qualify as allies. Fragile alliances that depend on the U.S. defense may be seen as burdens that are of no use to that balance. Yet no matter how much U.S. defense commitments waver, allies with no alternative but the United States find themselves in a difficult position.
Japan is the most vulnerable ally lacking autonomy because it adheres to an exclusively defense-oriented policy under the constraints of its pacifist Constitution and relies on the United States for deterrence. To transform the one-sided Japan-U.S. security treaty into a mutual defense treaty, constitutional revision is necessary.
Despite such vulnerability, the Trump administration appears to be positioning Japan as part of a group of major powers known as the "C5 (Core Five)," along with the United States, China, Russia and India. This stands in stark contrast to the apparent marginalization of European countries in the "U.S. National Security Strategy" released at the end of 2025.
In addition to the high regard for Japan's comprehensive national power, Prime Minister Sanae Takaichi's strong domestic base and Japan's historically friendly ties with Iran constitute valuable assets that can be leveraged in deal-based diplomacy among major powers.
The Japan-U.S. summit between Takaichi and Trump took place at a time when steering the alliance was the most challenging. Moreover, amid escalating tensions in the Middle East, Japan had to find a solution that would satisfy both the United States' request to send vessels to the Strait of Hormuz and Iran's demand for non-intervention.
Even under such circumstances, it was successful in that Japan avoided allowing the issue of dispatching vessels to become a point of contention. In a joint statement with countries such as Britain, France, Germany, and Italy, it conveyed its position that it was "ready to contribute to appropriate efforts" toward the early deescalation of the fighting and the subsequent safe navigation of vessels, securing U.S. acceptance.
Going forward, Japan must continue to pursue its unique approach of quiet mediation diplomacy to facilitate communication between Iran and the United States. It should also seek ways to give concrete form to the joint statement, such as leading a multinational mine-sweeping effort (a maritime task force) to ensure safe navigation after a ceasefire.
Yasuhiro Takeda was born in 1956 in Nagoya. He graduated from Hokkaido University and earned a Ph.D. from the University of Tokyo. He retired at the end of March 2026 as a professor at Tokyo International University, where he moved from the National Defense Academy. His field of expertise is international politics and security studies. His works include "The Cost of the Japan-U.S. Alliance," among others.
