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Aegis Afloat

The new missile defense policy incorporates the construction of two vessels equipped with the Aegis anti-ballistic missile system, as an alternative to the scrapped plan to deploy the land-based Aegis Ashore missile defense system. Defense Minister Kishi Nobuo said Japan must build a robust missile defense system in view of the heightened threats posed by North Korean missiles. Kishi told reporters on Friday that the government will thoroughly consider what kind of equipment will be mounted on the new Aegis vessels and how it should be operated by taking account of the changing situation.

In the areas surrounding Japan, China and Russia deploy a great number of ballistic missiles which can deliver nuclear weapons. Ballistic missile test launches by North Korea have made the threat of ballistic missiles a reality. In order to ensure readiness in response to armed attacks by ballistic missiles and other objects, Japan started developing the BMD system in 2004.

By the end of fiscal year 2010, the Aegis destroyers of the MSDF, “Kongo,” “Chokai,” “Myoko,” and “Kirishima,” completed equipment with BMD capabilities. Regarding the Patriot PAC-3, the ASDF successfully modified a total of 16 fire units of the 1st Air Defense Missile Group (Iruma), the 2nd Air Defense Missile Group (Kasuga), the 4th Air Defense Missile Group (Gifu), the Air Defense Missile Training Group and the 2nd Technical School (Hamamatsu) into PAC-3 capable units.

Concerning Aegis Destroyers, in addition to the existing four “Kongo” class Aegis Destroyers, two “Atago” class Aegis Destroyers are to be equipped with BMD capabilities. Regarding the Patriot PAC-3, one more fire unit of the 5th air defense missile group (Okinawa) will be upgraded into a PAC-3 capable unit. In parallel with the realignment of the existing PAC-3 units, every air defense missile group will have BMD capable PAC-3 fire unit.

The government considered introduce the Terminal High Altitude Area Defense (THAAD) mobile ground-based missile defense system. But Japan would need at least six units to cover the entire country, while Aegis Ashore required just two units. In 2017, Japan decided to deploy two batteries to the Ground Self-Defense Force (GSDF) training areas. Two years later, it chose Akita’s Araya district and Yamaguchi’s Mutsumi for the deployment which was to take place by 2025.

Japan's Defense Minister announced 15 June 2020 the country was cancelling plans to deploy a costly, land-based U.S. missile defense system designed to counter escalating threats from North Korea. Defense Minister Taro Kono told reporters he has decided to "stop the deployment process" of the Aegis Ashore missile system after discovering safety concerns regarding two communities near where the system would be based. Kono said the way the system was currently designed, they could not guarantee that the rocket booster from the missile system would not fall outside the Ground Self-Defense Force's Mutsumi base in Yamaguchi, southwestern Japan.

By 01 August 2020 the Japanese government was considering three main options to replace the halted Aegis Ashore land-based missile shield. A recommendation approved by defense-related panels in the ruling Liberal Democratic Party urges the government to quickly come out with "concrete proposals" to fill the gap left by the absence of the land-based missile shield, which was put on hold last month due to cost concerns.

The three main possibilities were: building a radar system on land that would detect incoming missiles to be shot down by ship-based interceptors, adding more Aegis-equipped ships to the existing fleet, and building a large offshore structure - a megafloat - to house both the radar system and interceptors.

A remote radar system would let the government install the interceptor battery in a location that would minimize the risk of booster rockets falling on residential neighborhoods. Adding more Aegis ships would be expensive to build, and the 600 crew members would be required to staff even two would further strain the chronically understaffed Maritime Self-Defense Force. An artificial island would be vulnerable to threats such as torpedoes and terrorist attacks.

Japan told the United States 06 September 2020 that it viewed building specialized ships to counter ballistic missiles as the most viable alternative to the scrapped plan to deploy land-based, US-developed Aegis Ashore systems. Building vessels equipped with the radar and missile launch system initially destined for Aegis Ashore, whose functions were only limited to countering ballistic missiles, would be cheaper than adding more Aegis-equipped destroyers capable of responding to attacks from fighter jets and submarines as well. The plan emerged as outgoing Prime Minister Shinzo Abe was expected to issue a statement by mid-September to explain the government's stance on missile defense, including the possibility of Japan acquiring a strike capability against missile bases in other countries, as Tokyo sought to review its security policy.

There are several reasons why building specialized ships to counter ballistic missiles is the most viable alternative. The first is trying to fill the shortfall of an arms deal with the US as it canceled the previous plan to deploy Aegis Ashore systems. The plan to build specialized ships would not require local consent, and would curb cancellation fees for Aegis Ashore equipment such as Lockheed Martin Corp.'s SPY-7 radar system, which can be loaded onto the envisioned ships.

Second, Tokyo hoped to reduce the sensitivity of the project to avoid being criticized by other countries in the Asia-Pacific region. Judging from the name, building specialized ships to counter ballistic missiles seemed to underline the defensive and lowering sensitivity. South Korea's plan to deploy Terminal High Altitude Area Defense in 2017 caused relations with many neighboring countries to deteriorate. Tokyo appeared to have drawn a lesson from Seoul's experience.

Third, the effect of sea-based deployment would be better than land-based. Sea-based deployment to counter ballistic missiles will increase its flexibility to deal with potential attacks. Article 9 of the Japanese Constitution outlaws war as a mean to settle international disputes involving the state. The article requires, Japan to formally renounces the sovereign right of belligerency and aims for international peace based on justice and order. Building specialized ships to counter ballistic missiles does not contravene Article 9 on surface. There have been reports saying the US is considering deploying mid-range missiles on Japanese soil. Such a move will irritate Japan's neighboring countries including China, North Korea and Russia. By contrast, building specialized ships to counter ballistic missiles conveys the idea that Japan is only improving its defensive capability.

And fourth, the sea-based deployment could carry more AEGIS Standard Missile interceptors than the existing DDG missile destroyers, for two reasons. The DDG missile loadout must also include anti-aircraft and anti-ship missiles to account for the destroyers other mission requirements. And the sea-based deployment could carry a larger vertical launch system that the DDG, because it is unconstrained by other design tradeoffs.-

Specialized ships to counter ballistic missiles can be significantly smaller and less expensive than AEGIS destroyers. Japan's national land area of approximately 380,000 km is the 61st place in the world, but the ocean area of the territorial sea + exclusive economic zone (EEZ) covered by resource development rights is actually about 4.47 million km2 and the 6th place in the world, making it abundant minerals on the seabed. The long-cherished desire of Nippon in the Far East is to establish its own energy. The large-scale offshore wind power generation business is becoming the mainstream as a European power generation system that prioritizes environmental issues. Various offshore vessels such as AHTSV (Anchor Handling tug supply vessel) and PSV (Platform supply Vessel), are expected to be introduced in anticipation of future development/scale expansion of offshore business in the territorial waters and exclusive economic zone of Nippon.

Offshore support vessels have high stability/operability even in stormy weather. PSVs are known as the "Sea trucks," as they are used primarily to transport materials and fuel to oil and gas field development rigs. When drilling rigs are transported to different locations, AHTS vessels are used to reel up the anchor from the seabed, tow rigs and support seabed pipeline laying. Both PSV and AHTS are equipped with dynamic positioning systems (DPS) that use the vessel's own propulsion equipment to maintain a fixed position.

A representative AHTS from Kawasaki Kisen Kaisha, Ltd “K” Line is 95 meters long with a breadth of 24 meters and a deadweight displacement of 4,800 Tons.

Officials had considered the option of special-purpose ships dedicated to intercepting missiles. Such vessels would cost less, but the idea was abandoned since they are vulnerable to submarine or air attacks.

Japan considered using a large ship as an alternative to the Aegis Ashore missile defense system. Kyodo News reported 01 November 2020 that the Defense Ministry was condiering a 9,000-ton [light displacement, ] ship to mount the new Aegis system, allocating larger living space for crew. If realized, it would be the largest Aegis-equipped vessel of the Maritime Self-Defense Force. The larger ship wsa needed because the new SPY-7 radar's height required a vessel beam greater than that of the conventional Aegis destroyers.

The proposed 9,000 ton light displacement [probably 11,000 tons full loaded] exceeded that of the Maya, the largest Aegis destroyer, with a light displacement of 8,200 tons [full displacement of 10,000 tons]. Some sources suggested that possibly a final pair of hulls could be completed to the revised specification including AN/SPY-7 radars, but adding beam to the hull might pose a challenge.

In June 2020 the government cancelled plans to deploy the shore-based anti-missile complexes, saying the deployment in the prefectures of Akita and Yamaguchi would put residents at risk of falling rocket boosters. The ministry also said that modifying the technology would take years and cost too much.

As a substitute measure, the ministry focused on two possible options -- remodeling private-sector vessels to mount the Aegis system and building dedicated maritime ships with the system. The decision would be made around the end of 2020 after the ministry received an interim report in mid-November from two private firms studying with the issue.

In July 2021 it was reported that the Defense Ministry plans to use Lockheed Martin Corp.’s SPY-7 radar system for its planned Aegis-equipped vessels, though the system is intended for use on land. The Aegis ships will be built as an alternative to the Aegis Ashore ground-based ballistic missile defense system,

Aegis Afloat

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Page last modified: 06-09-2021 15:33:41 ZULU