Over nearly seven decades, Japan has relied on commitments from the United States, its most important ally, for protection in the event of an enemy attack. Japan hosts the largest contingent of overseas American troops and regularly conducts drills with them. It has purchased more American-made F-35 stealth fighter jets than any other country outside the United States.
Yet now, as Russia’s invasion of Ukraine challenges long-held security assumptions and as threats from China and North Korea multiply, Japan is starting to rely more on itself, a shift that could quietly alter the balance of power in Asia.
The country’s governing party is pushing to increase Japan’s defense budget drastically, develop more military hardware domestically and redefine what it can do with those weapons under the pacifist Constitution in place since the end of World War II.
By asserting its own deterrent power, Japan — the world’s third-largest economy — could become less a military protectorate of the United States and more an equal partner. That could help fulfill the desire of American leaders for Japan to serve as a stronger military counter to China, as Beijing uses its rapidly improving armed forces to menace Taiwan and send ballistic missiles and coast guard ships into Japan’s territorial waters.
Japan must also confront a more bellicose North Korea, which has launched flurries of missiles — including one that flew over Japan’s northernmost island — in recent weeks, seemingly emboldened to expand its nuclear arsenal while the world grapples with the war in Ukraine.
At a meeting of Southeast Asian nations and their allies in Cambodia over the weekend, Prime Minister Fumio Kishida of Japan noted that Taiwan’s stability “directly impacts” regional security, and criticized Beijing for “intensifying” activities that threaten to violate Japan’s sovereignty in the East China Sea. And in a meeting with President Biden and President Yoon Suk Yeol of South Korea, the three leaders vowed to take “resolute steps” to denuclearize North Korea.
It is a delicate geopolitical moment that requires deft juggling. While Japan wants to demonstrate that it is a potent military force in its own right, it does not want to antagonize China, an important trade partner, or spook neighbors in Southeast Asia that want to avoid taking sides and might view Japan’s muscular security posture as a risk to regional stability.
But some defense experts say Japan must be more realistic about the limits of American protection, with the United States preoccupied by war in Europe and an erratic American political landscape in which changes of administration can lead to swift swings in policy.
“If we are in a crisis situation, will the U.S. military come to our rescue in all cases?” said Shigeru Iwasaki, a retired general and chief of staff to the Japanese Air Self-Defense Force.
Ultimately, with Japan nearly surrounded by threats, its effort to become more self-sufficient is intended not to distance it from the United States’ protective umbrella, but to ensure that Tokyo’s bond with Washington remains strong.
“We have to fortify our defenses in order to fortify the alliance,” said Ichiro Fujisaki, a former Japanese ambassador to the United States. “We can’t let the Americans do everything, and we have to do more on our own.”
A growing piece of Japan’s self-reliance is the development of domestically manufactured missiles that could be used to defend against foreign attacks or that might even be able to reach targets inside enemy territory. The Defense Ministry has also started a project to build a new fighter jet and is testing hypersonic missile defense technology.
There are questions about whether Japan has the expertise to develop cutting-edge military hardware. In 2021, less than 2 percent of all government-sponsored research was allocated to defense in Japan, compared with close to half in the United States and 10 percent in France, according to data from the Organization for Economic Cooperation and Development.
But last year, the Japanese government authorized record-high research and development spending within its overall defense budget, more than double the level of five years earlier. This year, the defense ministry has made another record-setting request that includes a greater emphasis on domestic weapons development.
The governing Liberal Democratic Party has proposed that Japan increase its defense budget to 2 percent of economic output over the next five years — up from about 1 percent — a goal that would align with members of NATO. The cabinet of Prime Minister Kishida will issue its official budget plan next month, and Parliament will vote on it early next year.
Until recently, the Japanese public balked at any proposal to drastically change defense spending. Now, as Russia’s invasion of Ukraine has triggered fears that China might seek to consolidate its authoritarian power and invade Taiwan — which lies less than 100 miles west of Japan’s southernmost islands — recent polls show that more than half of the Japanese public supports a significantly expanded defense budget.
Officials say Japan will continue to purchase American or other Western-made equipment. Yet they say they need to procure more military hardware from Japanese manufacturers at a time when import orders can suffer delays or when spare parts are difficult to secure because of supply chain issues.
“If Japan only relies on American equipment, maintenance could be difficult,” said Itsunori Onodera, chairman of the Liberal Democratic Party’s Research Commission on Security and a former defense minister.
Mr. Onodera said Japanese military officials had also become increasingly frustrated that American manufacturers lock down classified technology they sell to Japan. As a result, he said, the Japanese military cannot adapt fighter jets or missile defense systems purchased from the United States.
Japan began developing a new fighter jet two years ago. It has spent more than 200 billion yen — about $1.37 billion — on the so-called F-X, which is being designed by Mitsubishi Heavy Industries, one of Japan’s oldest industrial conglomerates.
Japan’s defense ministry initially consulted with American defense contractors about a potential partnership, Mr. Onodera said. But “the U.S. said they don’t have a specific plan in place for a next-generation fighter jet,” he said. Japan is in discussions with the British government about a collaboration between Mitsubishi Heavy and BAE Systems, Britain’s largest defense contractor.
One appeal of a British partnership is more open technology sharing, said Tsutomu Date, an official in the aircraft project management division within Japan’s defense ministry. BAE declined to comment.
Lt. Col. Martin Meiners, a Defense Department spokesman, said the United States supported Japan’s “cooperation with like-minded allies and partners, including the United Kingdom,” adding that the U.S. and Japan “are bolstering our defense cooperation in a number of promising areas.”
Still, by choosing a British partner, said Christopher W. Hughes, a professor of Japanese studies at the University of Warwick, Japan is “trying to somewhat hedge its bets and to retain some autonomy in its security ties.”
Some experts say Japan does not have the knowledge to develop a sophisticated fighter jet, and they suggest that the government is using defense spending to subsidize domestic manufacturers.
The F-X project is a “dream for the engineers,” said Yoji Koda, a retired vice admiral in Japan’s Maritime Self-Defense Force, but “to defend our country against an enemy threat and should war break out, we have to win. Our own indigenous developed fighters should be able to kill the enemy if necessary. Where is the guarantee?”
Analysts also question Japan’s decision to fund domestic development of a variety of missiles, including those that could attack enemy targets abroad.
In an interview in his office, Mr. Onodera demonstrated the prospective capabilities of the new missiles being developed by Mitsubishi Heavy.
He pointed to a pair of business cards on the table in front of him: these represented Japan. About two feet away, he set down a large mailing envelope: an unnamed enemy country. Two small plastic bottles of green tea stood in for Japanese and enemy ships or jets.
He brought the bottles lid to lid in the air above the table to demonstrate how a missile launched from Japan might hit an incoming missile. Landing one of the tea bottles onto the envelope, he suggested another possibility: a Japanese missile might fly all the way to a target inside enemy territory.
Mr. Onodera acknowledged that Japanese law was unclear on whether missiles could target sites inside another country.
Given that ambiguity, analysts question whether spending to develop missiles with extended ranges was a wise use of government money, especially as the rapidly aging, debt-laden country faces questions about how to afford a big jump in defense spending.
Defense experts say more urgent spending is needed to build better shelters for existing aircraft, install communication and backup fuel lines, and shore up munitions stockpiles.
By protecting what Japan already has, said Jeffrey Hornung, a senior political scientist at the RAND Corporation who specializes in Japanese security, “when a Chinese strike does come, their capabilities can survive an attack.”