CNAS | Insights Japan isn’t rearming. It’s adapting to a new era.

Japan’s defense posture is changing and changing fast. Military spending has increased sharply over the past four years. Japan’s Self-Defense Forces (SDF) are acquiring long-range strike capabilities, and Tokyo recently relaxed longstanding restrictions on the export of lethal weaponry. Japan is building a joint operational command and just launched a centralized intelligence bureau. Two modified destroyers today function effectively as aircraft carriers, Japan’s first since 1945.

To some, these advances amount to rearmament after eight decades of Japanese pacifism. Chinese officials have warned against a military buildup, and Foreign Minister Wang Yi last year said that countries must “resolutely prevent the resurgence of Japanese militarism.” Russia joined Beijing in calling for Tokyo to “make a clean break with militarism.” Charging Japan with rearmament or remilitarization has served as a convenient shorthand for some Western and Asian analysts, too.

Japan is indeed undergoing a defense revolution today, but it’s not rearmament. The SDF has for years represented an advanced, highly capable military force. While it is growing stronger, more important than the additions are what is being removed. Tokyo is systematically eliminating the self-imposed constraints that hobbled Japanese defense for decades. It is adapting to a new, more threatening Indo-Pacific security environment and greater global uncertainty. Washington should welcome and assist this transformation.

Already Armed

For decades after World War II, Japan was pacifist but certainly not unarmed. Tokyo spent, for example, a higher percentage of its GDP on defense in the 1950s than it does today. By 1989, largely as a result of the strong yen, Japan briefly had the world’s third-largest defense budget. In the early 1990s, the ground SDF was about a fifth larger than it is today, and it once had nearly twice the number of tanks it now possesses. Claims that Japan is rearming today suggests that Tokyo was unarmed in previous decades. Nothing could be further from the truth.

It was, however, constrained in significant ways. A product of its previous aggression, postwar Japan restricted its military to defense of the home islands. It could not engage in collective self-defense, banned the export of lethal weapons, did not possess the ability to strike long-range targets in foreign countries, and lacked a joint command. The SDF was capable in many ways but still dependent on the United States for fundamental defense, as well as weapons supplies and intelligence.

All of this is now changing rapidly.

The New Era

In 2022, Japan’s National Defense Strategy sounded the alarm in uncommonly direct terms. “Amid the most severe and complex security environment since the end of WWII,” it said, “Japan needs to squarely face the grim reality and fundamentally reinforce Japan’s defense capabilities.” The combination of China’s growing power projection and its aggressive foreign policy—including pressuring Taiwan, patrolling the Senkaku Islands, employing economic coercion, militarizing the South China Sea, and engaging in gray-zone activities in the western Pacific—focused minds in Tokyo. Russia’s invasion of Ukraine in 2022 further alarmed Japanese political leaders and defense planners. Suddenly the unthinkable—the forcible conquest and annexation of sovereign territory—was possible, then in Europe but perhaps tomorrow in Asia.

The stimulus for Japan’s defense revolution has only increased in intensity since then. China continues to grow in military strength and ambition, and North Korea remains a stubborn and nuclear-armed provocateur. And then there is the United States, Japan’s sole ally and the guarantor of the country’s security. American reliability and focus are newly in doubt.

The Trump administration has had an inconsistent approach to the alliance. At the operational level, the two countries have never worked together more closely. President Donald Trump oscillates between praise for Prime Minister Takaichi Sanae and criticism of Japan for ripping off the United States. The administration imposed tariffs on Japan and demanded that it raise defense spending as well as clarify its role in a Taiwan contingency. After Takaichi publicly did so, China retaliated with a raft of punitive measures that elicited mostly silence from Washington. Japan strives to focus American attention and resources on the Indo-Pacific but watches as yet another costly and inconclusive war in the Middle East absorbs Washington’s attention. A poll last year showed that more than 75 percent of Japanese did not believe the United States would defend their country.

Tokyo’s pursuit of a more powerful, less-constrained military serves two purposes simultaneously. Japanese leaders seek to demonstrate their value to the alliance, helping assure America’s continued commitment. But a stronger military also helps Japan hedge, both against the region’s rising threats and the possibility of U.S. inconstancy. Takaichi’s moment of domestic political dominance has freed the Liberal Democratic Party to unshackle its defense policy. And it is doing so quickly.

The Great Unshackling

The acquisition of new defense capabilities has been particularly striking. Japan has bought long-range strike weapons, including Tomahawk missiles that allow it to hit targets more than 1,000 kilometers away. It effectively has two aircraft carriers and F35 aircraft that can fly from them. Japan is developing a hypersonic glide vehicle, working on joint development of a sixth-generation fighter, and seeks nuclear-propelled submarines. As global demand for missile interceptors vastly outstrips supply, Japan is manufacturing Patriots—and selling them to the United States.

Budgets continue to rise, and Takaichi pledged to hit the previous target—spending 2 percent of GDP on defense—two years early. Japan will be just under this figure at the end of 2026 and is sketching out future increases. Today, Japan has become the world’s tenth-biggest defense spender. The organizational framework is changing as well. Japan last year established a new Joint Operations Command that will allow for quicker, more effective decision-making and planning.

In April, Japan relaxed its longstanding ban on the export of lethal weapons and has sealed a multibillion-dollar deal to sell warships to Australia. Its newly announced National Intelligence Bureau represents the first centralized intelligence agency in Japan since 1945. Japan and the United States have begun a dialogue on extended nuclear deterrence. And by the end of this year, three key strategic documents—the National Security Strategy, the National Defense Strategy, and the Defense Buildup Program—will be rewritten and reissued. Perhaps most ambitiously, Takaichi in May called for a debate on revising the Japanese constitution, ensuring that it is “updated to reflect the demands of the times.”

The U.S. Role

Washington should welcome Japan’s defense transformation, which will strengthen the alliance and enhance deterrence in the western Pacific. The United States is making its own positive moves, including standing up a joint operational headquarters to work with Japan’s new Joint Operations Command. It has increased its work with Tokyo on cybersecurity and enhanced operational planning across the board.

The United States could usefully avoid the kind of inconstancy and economic harms that have characterized the past year and a half. Demanding that Tokyo spend a constantly changing percentage of GDP on defense does not assist those who wish to expand Japan’s defense capabilities. Imposing tariffs sours Japan’s domestic politics and harms its economy. Washington should have backed Tokyo far more vocally after China imposed punishment for Takaichi’s comments on Taiwan.

Washington can play a positive role as well. In establishing a central intelligence bureau, Japan will need to strengthen its information and cyber security, and the United States can help with both. It should continue to operationalize the alliance for wartime scenarios, with all the necessary training and planning. It can aid the defense industrial base by buying Japanese, especially in ships and munitions. Washington can help Tokyo buy wisely, thinking hard about whether expensive projects like nuclear-propelled submarines are necessary and whether developing a sixth-generation fighter is realistic. Japan carries the highest debt-to-GDP ratio of any advanced economy and has an aging population; there will be inevitable limits to its defense spending.

Above all, however, the United States should welcome Japan’s emergence as a “normal” country, one that is active not just at home but in its region and that has a defense posture and policy befitting a key American ally. Tokyo today is not rearming but relaxing the many constraints that tied down its military. Eight decades after the worst war in history, and at a time of rapid geopolitical disorder, the United States should help usher in Japan’s adaptation to a new era.

Richard Fontaine is the chief executive officer at the Center for a New American Security.