Japan's security strategy at a crossroads

“Shields and spears” is the longstanding security strategy that has defined the Japan-US alliance. In it, Japan plays the role of the shield, while the US is the spear. But Tokyo’s decision to suspend its plan to deploy Aegis Ashore units may signal a major shift in the strategy.

Japan was planning to purchase two Aegis Ashore land-based missile defense systems from the US to protect itself from the North Korean threat, deploying them in Akita and Yamaguchi prefectures. The systems were set to be operational as early as 2025.

But last month Japanese Defense Minister Kono Taro suddenly announced the program was being suspended, citing the need for an overhaul to ensure the boosters guiding the defense rockets would not pose a threat to civilians. The future of the program is now unclear.

The original decision to deploy Aegis Ashore was said to have been influenced by the close relationship between Prime Minister Abe Shinzo and President Donald Trump.

Murano Masashi, an expert on Japan-US security policy at the Hudson Institute in Washington, says the situation is complex.

“The US government was very supportive of Japan's decision to purchase the Aegis Ashore system,” Murano says. “I think they’re embarrassed by the cancellation of the deployment plan, particularly the office of the Secretary of Defense. Still, there is a consensus in both Tokyo and Washington that the US-Japan relationship cannot be allowed to deteriorate. Both governments need to make sure that damage to the alliance is minimized in the face of the serious missile threats from China and North Korea.”

Murano Masashi, Japan chair fellow at Hudson Institute.

The Aegis Ashore units were expected to supplement existing PAC3 interceptor missiles and Aegis-equipped destroyers to provide full coverage against a possible missile attack from North Korea.

In the wake of the government’s decision to pull out of the deployment agreement, Prime Minister Abe said his administration would discuss the overall direction of the country’s security strategy.

“What should we do to strengthen our deterrence and improve our response?” Abe said at a news conference on June 18. “We will discuss this thoroughly at the National Security Council.”

As an alternative, the government has been considering increasing the number of ships equipped with the Aegis system. But some members of the ruling Liberal Democratic Party are saying this is not enough, even calling for the ability to strike enemy targets.

The exact term in Japanese that lawmakers are using refers to the “capability to attack enemy bases,” a concept reminiscent of the idea of a preemptive strike. For example, if North Korea gave off signs that it was planning an imminent missile attack, Japan would have the ability to strike missile bases before weapons could be launched.

This could be carried out with long-range cruise missiles fired from fighter jets. The Japanese government maintains that this kind of strike capability falls within the country’s right to self-defense.

But interpretation of this right remains a highly contentious issue within the country, given the constitutional clause renouncing war. The LDP has pledged to modify this clause, but no changes have so far been implemented as its ruling coalition partner, the Komeito party, is more cautious on the issue.

Ironically, abandoning the Aegis Ashore program, which was meant to be the ‘shield’ in the US-Japan ‘shields and spears’ strategy, could lead to Japan acquiring its own spear in the form of missile strike capability. Such a development would not only mark a significant change in the tenor of the alliance, but would also be a seismic shift in the regional geopolitical balance.