Following Japan's decision to scrap a plan to deploy the land-based Aegis Ashore ballistic missile defense system, the country is expected to face difficulties in finding an alternative means of protecting itself from the threat of North Korean missiles.
Defense Minister Taro Kono has indicated Japan will for the time being defend itself from the missile threat with the existing Aegis-equipped destroyers of the Maritime Self-Defense Force.
But making them focus on missile defense would mean they cannot be used for defense elsewhere, including the Nansei Islands chain covering Okinawa, around which China has recently been increasing its maritime activities.
While the new Aegis-equipped destroyer Haguro will be added to the fleet next March, bringing the number of such vessels to eight, a defense ministry source said increasing them further requires the training of crew, which "cannot be achieved overnight."
U.S. forces use the advanced land-based Terminal High Altitude Area Defense (THAAD) system. But like Aegis Ashore, it faces the problem of cost and limitations on where it can be deployed.
The Defense Ministry considered introducing THAAD in the past but decided against it due to its huge costs.
Some members of the ruling Liberal Democratic Party have proposed that Japan be able to attack foreign enemy bases. They believe interceptor missiles may be ineffective at a time when countries such as North Korea are enhancing their missile technology.
"We need to consider various means of deterrence to stop missiles from coming," said Itsunori Onodera, chairman of the LDP's Research Commission on National Security, who was defense minister in 2017 when the government decided to deploy the Aegis Ashore system.
Komeito, the LDP's junior coalition partner, has reacted negatively to the idea of adopting a strike capability.
Komeito leader Natsuo Yamaguchi told a news conference Tuesday that he hopes to "hold careful discussions" based on the government's long-held practice of preventing the ability to attack foreign enemy bases, in line with the country's exclusively defense-oriented policy under the pacifist Constitution.
Meanwhile, the U.S. government said Thursday it will continue to cooperate with Japan in relation to ongoing security challenges in the region.
"We will continue to work closely with Japan to find a solution to their concerns that enhances our shared security in the face of growing regional threats," a State Department spokesperson said in a statement.
The Aegis Ashore system was expected to add a layer of protection to Japan's existing two tiers of missile defense, but the government found that potentially costly and time-consuming upgrades would become necessary to ensure the safety of nearby residents during Aegis Ashore missile interception operations.
Under the current system, the MSDF's Aegis destroyers equipped with Standard Missile-3 interceptors are tasked with destroying missiles in the outer atmosphere. If they fail, the Air Self-Defense Force's ground-based Patriot Advanced Capability-3 interceptors are the next line of defense against missile attacks.