Japan’s nationalist moves that have infuriated the victims of its past militarism are posing challenges to the U.S. drive to beef up cooperation among its allies in the face of an increasingly assertive China.

Its preeminent politicians including Prime Minister Shinzo Abe have recently churned out controversial remarks that showed their refusal to atone for their country’s wartime atrocities, raising the ire of South Korea and China.

From Washington’s standpoint, the core ally’s rightward shift spurred by nationalism appears worrisome, though some observers dismiss it as merely rhetorical ahead of the upper-house elections slated for July.

“The U.S. is concerned that the sharp deterioration of the relationship, particularly between Japan and South Korea. … We are concerned that some of the steps that have been taken have led to a greater distrust (between the two),” Kurt Campbell, former assistant U.S. secretary of state for East Asian and Pacific affairs, said during a Seoul forum last month.

“I think privately, behind the scenes, the U.S. and others have urged caution and prudence. I think the general watchword of diplomacy in Northeast Asia, frankly, is that in most circumstances, history is best left to the historians.”

The biggest headache for the U.S. originates from the fact that its strategy to strengthen security cooperation with the two key allies ― South Korea and Japan ― in handling potential security risks from North Korea and China is faltering due to their deepening historical enmities.

“The reason why Washington might feel uneasy over the Abe administration’s anachronistic historical perspectives is that the three-way security cooperation, a means to manage China’s rise, is adrift,” said Nam Chang-hee, security expert at Inha University.

“I believe Washington would continuously send messages to Tokyo that it would not let slip by its historical revisionism that would needlessly strain Korea-Japan ties.”

Refocusing its diplomatic and military attention onto the region, the U.S. has sought to bolster joint military drills with South Korea and Japan, but Seoul has remained reluctant to join them as public sentiment has worsened against Tokyo.

Last month, U.S. Joint Chiefs of Staff Gen. Martin Dempsey stressed the need to integrate missile defense systems of the U.S., South Korea and Japan to better deal with a potential North Korean attack.

But much of the South Korean public remains reluctant over any military tie-up with its onetime colonizer as witnessed last year when the two countries’ push to sign a military-information-sharing pact foundered amid strong public protest.

Particularly at a time of financial difficulties, Washington may prefer to maintain the status quo in the Asia-Pacific region, where some power shift has emerged amid the rise of China, observers noted. But Japanese right-wingers’ words have reignited destabilizing regional conflicts.

Another concern for the U.S. is the possibility that nationalist responses to a long-simmering dispute over a set of the islands in the East China Sea ― called Senkaku in Japan and Diaoyu in China ― could lead to an unintended crisis when the U.S. seeks stability after a decade of war in Iraq and Afghanistan.

Washington and Tokyo have reportedly been working on crafting a joint military plan to respond to a contingency over the islands, which some argue could help restrain Japan and prevent an escalation of a possible crisis.

The U.S. has also signed a joint counter-provocation plan with South Korea when its ally has vowed to take a retaliatory strike ten times stronger than any provocation by North Korea.

“The U.S. has had a number of assertive allies ― countries by national pride anxious to deter adversaries and strengthen their security,” said Bruce Bennett, a security expert of the RAND Corporation.

“When those allies have been relatively weak, they have been forced to rely more on U.S. power and U.S. preferences, but when they become strong, they prefer to exert more of their own strength and are less willing to be constrained by the U.S.”

He added forging a “balanced” deterrence strategy for its allies facing security threats is a tough task for the U.S.

“U.S. allies could escalate into unintended and even unwanted crises, but at the same time too weak a response to adversary actions can also encourage further adversary provocations. Reducing adversary threats while avoiding escalation is a very delicate balance,” he said.

Although Japan is a vital U.S. ally that shoulders a hefty cost for the upkeep of some 50,000 U.S. troops based in the archipelago state, the U.S. might find it difficult to just shrug off remarks that undermine international human rights norms, experts noted.

Toru Hashimoto, Osaka mayor and co-leader of the nationalist Japan Restoration Party, has made headlines in recent weeks, saying wartime prostitution was necessary to console soldiers and maintain their discipline.

“The U.S. views the issue of wartime sex slaves as an issue of the violation of international norms. (The denial of sexual slavery) would be burdensome even though Japan is a core ally in terms of security and the economy,” said Lee Jung-hwan, assistant professor at the School of International and Area Studies of Kookmin University.

With Tokyo failing to repent for its past, its drive toward a constitutional revision has also stirred a controversy with South Korea and China, arguing it seems to be reviving Japan’s past militarism.

The Tokyo government is moving to revise Article 96 of the constitution to reduce the number of parliamentary votes required for a constitutional amendment and then possibly modify Article 9 that bans Japan’s right to wage war and possess potential war materials.

The U.S. does not appear opposed to the envisioned revision as Japan becoming a “normal state” with a full-fledged military could more effectively help its overseas military operations. But angry responses from Seoul and Beijing are big hurdles to the change.

“Because of Japan’s existing constitutional limitations, while the U.S. is obligated to assist in Japan’s defense should it come under attack, Japan cannot assist the U.S. militarily if the U.S. is under attack, even though the treaty is called the Treaty of Mutual Cooperation and Security,” said Balbina Hwang, former State Department advisor and international politics professor at Georgetown University.

“This is a serious limitation from the perspective of the U.S., and one major reason why the U.S. supports Japan’s revision of its Article 9 to allow for ‘normal’ militarization, beyond purely self-defense.”

Over the course of Japan’s contentious rightward shift, Japan might have lost some of its trust from its ally U.S. experts pointed out.

“South Korea used to be an ally, somewhat unpredictable and unstable from the U.S. perspective while Japan has been a responsible, reliable ally for the U.S. But with rightwing politicians’ explosive remarks, things appear to have changed,” said Sheen Seong-ho, professor of the Graduate School of International Studies at Seoul National University.

By Song Sang-ho (sshluck@heraldcorp.com)