Referenews

Around $3.7 billion is earmarked over the next five years for missile systems, including American Tomahawk missiles, which would give Japan the ability to target foreign military facilities if an attack appeared imminent. That is a turnaround from Tokyo’s postwar pacifist outlook, enshrined in its war-renouncing constitution, which made it wary of threatening other countries. 

The strategy document called the missile plans and other changes “a major transformation in our nation’s postwar national-security policy” designed to warn potential aggressors—mainly China, North Korea and Russia—that it would be too costly to attack Japan. 

Russia’s invasion of Ukraine and China’s rapid military buildup in recent years have driven a change in public sentiment in Japan, where many worried about a return to Tokyo’s militarist past. A majority of Japanese now support increased military spending, polls show.

“The public is already there and now they are pulling the politicians into that zone,” said

Rahm Emanuel,

the U.S. ambassador to Japan, who praised the new strategy. Before Russia’s invasion and China’s firing of missiles near Japan this year, he said, “this was going to take 10 years to get one of these things done.” Instead, “it all happened in one year,” he said. 

Prime Minister

Fumio Kishida

has warned in speeches that “today’s Ukraine could be tomorrow’s Asia,” reflecting concern about the possibility of China attempting to capture Taiwan by force. 

Those concerns were heightened by Chinese military exercises near Taiwan after U.S. House Speaker

Nancy Pelosi

visited the self-governed island in August. China launched five missiles that landed within Japan’s exclusive economic zone. 

Shedding Tokyo’s usual reticence over China, the strategy released Friday includes a long list of complaints about Beijing’s conduct, including its close ties with Russia and its incursions near Japanese-held islands.

Following debate within the ruling party camp about whether to call China a threat, the government settled on language describing China as “the biggest strategic challenge, unlike anything we have seen before.” The language mirrors Washington’s recently published defense strategy. 

Ahead of the strategy’s release, Beijing denounced it as a dangerous step that would lead Asian nations to question Tokyo’s commitment to peace.

“The Japanese side ignores facts, deviates from its commitment to China-Japan relations and the common understandings between the two countries and groundlessly discredits China,” foreign ministry spokesman

Wang Wenbin

said Wednesday. “Hyping up the ‘China threat’ to find an excuse for its military buildup is doomed to fail.”

Japan’s strategy document also reiterated concerns about North Korea’s nuclear weapons program and its recent string of missile launches. But it put North Korea below China on the threat list, reversing the order from a previous strategy released in 2013.

The spending plans commit Japan to ¥43 trillion, equivalent to $312 billion, in defense outlays over five years starting in the fiscal year that begins in April. That would bring Japan into line with spending targets shared by the U.S.’s European allies in the North Atlantic Treaty Organization.

Besides acquiring American Tomahawk missiles, Japan plans to extend the range of its own missiles so they can hit targets as far away as mainland China and be launched from ground, air or sea. All together, the plan calls for spending nearly $60 billion on new missiles and missile defense. 

The U.S. has for years encouraged Japan to spend more to defend itself. Under a security treaty signed following World War II, the U.S. guarantees that it would come to Japan’s aid if the country were attacked. 

Suntory Holdings Ltd. Chief Executive

Takeshi Niinami,

who has advised the government on economic matters, said “Japan has to demonstrate that we will defend our own country” to American policy makers who may be inclined to lessen overseas commitments.

“If we don’t take action to protect our own country, will our allied countries support us? I don’t think so,” Mr. Niinami said. 

The largest permanent contingent of U.S. forces overseas is located in Japan, including around 54,000 personnel. The home port of the U.S. Seventh Fleet, including the aircraft carrier USS

Ronald Reagan,

is in Yokosuka, just south of Tokyo.

Tighter cooperation with the U.S. is a theme of the new strategy and two associated documents also released Friday. They envision the U.S. and Japan acting as one, including in situations where Japan is attacking enemy bases. 

Partially prompted by U.S. concern, Japan committed around $7.3 billion over the next five years to improve its cyber defenses, including raising the number of core cybersecurity personnel to 4,000 from 890.

It said these steps would enable it to get greater access to U.S. intelligence, which Washington has sometimes been reluctant to share for fear that it would leak. Military analysts say Tokyo would likely rely on such intelligence to strike a foreign target with its missiles.

While the public is generally behind the defense plan, Mr. Kishida, the prime minister, faces unrest in his ruling party over how to pay for it. He has said he wants to raise taxes—and ruling-party leaders are calling for an increase in the corporate tax—but some lawmakers called the decision hasty and said it could hurt the economy.

—Peter Landers contributed to this article.

Write to Alastair Gale at alastair.gale@wsj.com and Chieko Tsuneoka at chieko.Tsuneoka@wsj.com