Neighboring countries have condemned a sharp increase in defense spending in Japan and significant changes to the nation's long-held security policies, with even nominally allied governments expressing concern about a burgeoning arms race in Northeast Asia.

The Japanese government announced on December 16 that it intends to dramatically ramp up defense outlays in the coming years, allocating 43 trillion yen (€296 billion/$323 billion) over the next five years and raising annual defense spending to 2% of the country's GDP by 2027.

The added investment includes the purchase from abroad or domestic development of advanced new fighter aircraft, drones, a new class of sophisticated diesel-electric submarines, long-range missiles and additional surface warships.

Investment will also be funneled into improved logistics abilities — a lesson learned from the Ukraine conflict — and improved cyber and space warfare capabilities.

In tandem with greater spending, critics suggest Tokyo is moving away from the commitment enshrined in its constitution — enacted after the nation's defeat in World War II — that explicitly forbids the use of force in international disputes.

A key element of Tokyo's new military buildup will be the development and deployment of weapons able to strike an enemy base if it is determined that an attack on Japan is imminent.

Growing security challenges in Northeast Asia

"Unfortunately, in the vicinity of our country, there are countries carrying out activities such as the enhancement of nuclear capabilities, a rapid military buildup and unilateral attempts to change the status quo by force," said Prime Minister Fumio Kishida, announcing the increase in spending on December 9.

North Korea — which in recent months has launched a large number of advanced new long-range ballistic missiles — is likely to launch a new missile-equipped submarine in the near future and is planning to carry out a seventh underground nuclear test.

China continues to fortify disputed islands and atolls in the South China Sea, in spite of international condemnation. Beijing has insisted Taiwan will be incorporated into the Chinese mainland, by force if necessary, and is embroiled in a series of territorial disputes with several of its neighbors, including Japan, India, South Korea, Vietnam and the Philippines.

North Korea was quick to respond to Japan's defense spending announcement, with a statement issued by the Foreign Ministry in Pyongyang declaring Tokyo was "bringing a serious security crisis to the Korean Peninsula and East Asia."

Accusing Japan of being "a war criminal state" and being in "wanton violation of the UN Charter," the statement claimed Tokyo is "seeking to gratify its black-hearted intention [and] arms buildup for re-invasion" of Korea. The ministry threatened that North Korea will respond with "actual action," although it did not specify its intentions.

In a statement issued through its embassy in Tokyo, the Chinese government said Japan's move "provokes regional tension and confrontation" and called on Tokyo to stop using what it termed the "China threat" to excuse its own military expansion.

Last Thursday, Russia joined the chorus of criticism, claiming Japan was abandoning decades of pacifist policy and replacing it with "unbridled militarism." A statement from the Foreign Ministry in Moscow said the decision will "inevitably provoke new security challenges and will lead to increased tension in the Asia-Pacific region."

Yakov Zinberg, a professor of international relations at Tokyo's Kokushikan University, said the criticisms from Japan's regional rivals, "Is in line with what I expected before the announcement."

Fears of an arms race in the region

"My fear is that we are close to spiraling into the vortex of an arms race in the region, and perhaps that has already started," he told DW.  

"The North Korean response was largely rhetoric and they will not actually attack Japan, but this response is symptomatic of our times," he said. "We have to be more worried about China and Russia, which have this week started joint military exercises in the East China Sea and that can only be seen as a message to Japan." 

Japan is also closely watching the movements of the Chinese aircraft carrier Liaoning, which is conducting landing exercises off the southern Japanese islands of Okinawa Prefecture, while three Chinese government patrol ships on Thursday intruded into Japanese territorial waters around the Senkaku islands in the East China Sea. China claims the uninhabited islands as its own territory and refers to them as the Diaoyutai archipelago.

Zinberg said he had been more taken aback by the reaction of Seoul to Japan's defense spending increase, with the government of President Yoon Suk-yeol stating it is "a grave matter" and warning that Tokyo needs to consult with Seoul for any security issues that involve the Korean Peninsula.

The South Korean media has been even more strident, with The Korea Times in an editorial demanding that Tokyo "not forget the lessons of the Pacific War," which ended nearly 80 years ago, and declaring that "Japanese right-wing groups have one goal: regaining their country's former military and political influence."

Another editorial, in The Korea Herald, said Japan's plans to develop a counterstrike capability "marks a dramatic policy change." It hinted that Tokyo could use its new-found military strength to "take more provocative acts" to reclaim South Korean-held islands half way between the peninsula and Japan, that Tokyo claims sovereignty over.

The islands are occupied by a South Korean police unit and are known as Dok-do; Japan insists they should be considered part of Japan and known as Takeshima.

Eunjung Lim, an associate professor of international studies at South Korea's Kongju National University, pointed out that relations between Japan and South Korea are "very complicated" due to the two nations' shared histories.

Question of trust between Japan, South Korea

"There are two main reasons for the response from South Korea," she said. "The first is simply the scale of the increase, which will give Japan the third-largest military budget in the world. South Korea cannot compete with that as our GDP is around one-third of Japan's, so people here think it is too much."

"But a more fundamental reason is that this goes against Japan's peace constitution," she added. "Japan now says it has the right to carry out a counteroffensive against an enemy military base when it detects a threat, but under our constitution, the North is still considered a part of Korea so that could be considered an attack on South Koreans." 

The root of the problem, Lim believes, is trust.

"I think that given the rising power of China and even the challenges posed by Russia, Japan had little choice but to revise its national security policies," she said. "But Korean people have traumatic memories of Japan's colonial rule of the peninsula and many people feel that we simply cannot trust Japan to be a reliable partner."

"Those concerns are now being amplified by conservatives and nationalists in the media and until their worries are fully addressed, then it might be difficult to trust Japan again," she said.

Edited by: Keith Walker