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Aegis Afloat - Analysis of Alternatives (AoA)

One week after the new administration was inaugurated on 04 October 2021, Defense Minister Kishi, who faced Prime Minister Suga at the official residence, was instructed to proceed with consideration of alternatives to Aegis Ashore. The government had been promoting a plan to deploy this Aegis Ashore at candidate sites for training grounds of the Ground Self-Defense Force in Akita and Yamaguchi prefectures. The Aegis Ashore plan was cancelled on 15 June 2020, due to the failure of the Ministry of Defense and the government to explain to local residents too much. And the alternative plan was to return to the sea as an Aegis ship.

The ostensible reason why the government decided to revise the Aegis Ashore plan in 2020 was the booster fall problem in Yamaguchi Prefecture, but the actual main reason was that the Ministry of Defense repeatedly made big mistakes in explaining to Akita Prefecture. Because if the booster drop was the only problem, there was no need to change the deployment to Akita, which was right next to the sea. Even if it was deployed to Yamaguchi, it should have been solved by placing only the launcher on the coast or in the ocean and remotely controlling it.

In other words, the government probably believed that it would be difficult to persuade the local residents with the plan on the ground, and that it would not be possible to make it a military force early on, and that even if the deployment location was changed, it would inevitably lead to strong opposition from the local people. Far from being on the ground, even the idea of ​​a mega-float on the sea near the coast and the idea of ​​a piled fixed offshore rig were abandoned at an early stage. It was the only method that could be deployed offshore. There was no other way to make it a force within five years.

On 24 September 2020, Defense Minister Kishi, who attended a defense-related meeting of the Liberal Democratic Party, revealed that he was considering deploying radar and other equipment on the sea as an alternative. The Ministry of Defense planned to use the Aegis Ashore, and would like to use the contracted "SPY-7" as an alternative. The Ministry of Defense proposed a plan to use escort ships, a plan to utilize commercial ships, and an alternative plan to set up a structure called a "rig" that looks like a device used for drilling oil fields. However, it was said that this did not mean "three choices".

On August 25, the Liberal Democratic Party National Defense Assembly Group subdivided the three proposals into eight proposals and presented them again.

1. Separate installation plan A (float)
2. Separate Installation Plan B (Private Vessels)
3. Separate installation plan C (escort ship)
4. Separate Installation Plan D (escort ship + Aegis ship)
5. Mega float/rig idea
6. Aegis warship reinforcement plan A (SPY-7)
7. Aegis warship reinforcement plan B (SPY-6)
8. Aegis warship increase B' plan (SPY-6 *SPY-7 was also used)

The separate installation plan and the megafloat plan use Lockheed Martin's SPY-7 radar for the Aegis system that had already been contracted, so there was no penalty. On the other hand, the Aegis ship reinforcement plan includes a plan to cancel the SPY-7 and switch to Raytheon's SPY-6. This was because the US Navy's newly built Aegis ships were equipped with SPY-6, so the same type of radar was more suitable for cooperation. However, there will be a SPY-7 penalty. In Plans C and D, which were separate installations, the SPY-7 radar on land and the escort ship on the sea were plans to work together, but the addition of a new Aegis destroyer to this plan will effectively be Plan B' for increasing the number of Aegis warships.

The separate installation plan A (float) and the mega float/rig plan were less feasible due to the problem of being placed on a fragile structure called a non-moving float, and the separate installation plan C and D use existing destroyers for ballistic missile defense missions. It will restrict you. Originally, the purpose of Aegis Ashore was to release the Aegis ships from their anti-North Korea and ballistic missile defense missions in the Sea of ​​Japan and to use them for their original mission, which was to confront the Chinese Navy in the East China Sea. Adopting plan D would end up putting the cart before the horse.

Under Plan B for separate installation (civilian ship), a private ship will be rented and equipped with an interceptor missile launcher to be used as an "arsenal ship" that will move offshore. If this was remotely controlled by Aegis Ashore on land, it will not restrain the escort ship, and unlike coastal floats, there was no need to worry about terrorist attacks by submersible agents from the sea. However, since it had no self-defense combat power, it was weak against full-scale attacks and cannot be placed on the front line like an escort ship.

This problem could be solved if the munitions ship was a cargo ship, but since it had no self-defense ability, it cannot be placed on the front line, and may be placed in the Pacific Ocean side of the rear instead of the Sea of ​​Japan. Since the SM-3 Block 2A interceptor flies beyond the atmosphere and had a very long range, even under these conditions it was probably possible to defend all of Japan with two locations.　The idea of ​​​​a ``arsenal ship'' that does not have missile operational capability and was remotely controlled by another ship had existed in the past in the United States as a discontinued plan called ``Arsenal Ship''.

The plan to build a dedicated interceptor ship surfaced, and the idea of "separately installing only the launcher at sea" was dropped, and all candidates were narrowed down to the idea of "deploying a complete radar and launcher system at sea". The reason why the plan to separately install only the launcher on the sea (with the radar placed on the ground) was dropped from the list of candidates seems to be largely because it was difficult to obtain the local understanding of placing the radar on the ground. Also, the reason why the idea of ​​placing a mega-float on the coast was changed to an oil drilling rig that can be placed offshore was probably because even on the coast, local opposition was strong and it will take time to persuade them.

Another concern about the separate installation plan was that the remote control of the radar and launcher would not function if communication was jammed by an electronic attack. 3 Block 2A interceptor missiles were to be operated in EOR, so I find it hard to believe the explanation that the separate deployment plan does not allow this. Because Japan planned to remotely control each other between Aegis ships.

Plan to install Aegis interceptor system on civilian ships was a proposal to remodel private cargo ships and tankers and install the Aegis interception system as a dedicated ship specializing in anti-ballistic missile interception. However, even though the launcher and radar were mounted on the same ship, it cannot be placed on the front line due to its lack of self-defense capabilities. If a civilian ship was equipped with an Aegis interception system and does not have self-defense capabilities, it had the advantage that the construction cost of the hull was much cheaper than a warship.

Aegis Ashore Afloat (AAA) was a plan to install an Aegis radar on a private container ship yhat had already been proposed in the United States. Its name was Aegis Ashore Afloat (AAA), Aegis that had landed will return to the sea again. This was not an official proposal of the United States Navy, but rather a 2N program for the purpose of training warship construction technology, which had been a partnership between the United States Navy and the Massachusetts Institute of Technology (MIT) since 1901.

However, this Aegis Ashore Afloat (AAA) plan was a plan to install only the Aegis system and radar, and the launcher was not installed together. This was a proposal based on the premise of remote engagement (EOR) in cooperation with other interceptor units, so it cannot be applied as it was to Japan's Aegis Ashore alternative. If you want to fight in a remote engagement, the launcher separation installation plan will be fine.

If the Aegis system, radar, and launcher were already installed on the same ship, then the illuminator (radiation radar for guiding atmospheric interception missiles) and sonar (for anti-submarine detection) were installed, and the launcher was in the atmosphere. Self-defense capabilities can be acquired by loading internal interceptor missiles and ASRock (anti-submarine missiles). Apart from the cost of ammunition, all you need was an illuminator and a sonar, and even if you cut it short, it won't cost much. Adding small things like autocannons and electronic jammers doesn't change the cost much.

In other words, the main purpose of installing the Aegis interceptor system on civilian ships was to reduce the cost of building the hull, and it does not mean that it will be cheaper if the self-defense ability was cut off. However, if there was no self-defense capability, it cannot be placed on the front line alone, and if placed on the Pacific side in the rear, the new radar cannot be used.

Aegis freighters were cheaper than Aegis destroyers, but they were flawed ships with no self-defense capabilities. On the other hand, if Japan was going to give a cargo ship self-defense capabilities, it seemed more appropriate in terms of cost and capability to compromise with a frigate (an escort ship that was slightly smaller than a destroyer) that had self-defense capabilities from the beginning.

The original oil drilling rig equipped with Aegis interceptor system plan was to install a mega float on the coast, but it was changed to a plan to install an oil drilling rig that can be installed offshore. This avoids delays in the plan due to local protests, and also provides technical advantages. Going offshore will not be a problem against tsunamis where the waves were high on the shallow coast, and by making it self-propelled, it will continue to move even at low speeds, making it more resistant to terrorist attacks.

However, as long as it was not placed on the coast, the operating personnel will not be able to commute from their homes, and as with the civilian ship installation plan, it will be necessary to return to the port regularly to take a rest or transport personnel by helicopter to replace them. Regular maintenance of the rig itself was also unavoidable because it will be damaged quickly as long as it was offshore with high waves, so it will be necessary to dock and repair it just like a ship. In other words, the advantages and disadvantages of this plan were not much different from those of civilian ships. A self-propelled oil rig that can be deployed offshore would be more resistant to terrorist attacks than a megafloat on the coast. North Korea's low maritime reconnaissance and maritime attack capabilities can also avoid attacks by regular forces. However, it was almost as vulnerable as a bare ground radar site to the Russian and Chinese forces, which have high enemy search capabilities. Without the ability to self-defense, the proposed oil rig would have the same problems as the proposed civilian ship.

However, the oil drilling rig plan and the civilian ship plan were plans to divert the Lockheed Martin SPY-7 radar for Aegis Ashore, which had already been contracted. Although this was technically possible, the US side had pointed out that the cost of refurbishment for sea deployment will increase. 　Aegis Ashore was originally selected for the reason that it was the most cost-effective among the many candidates for the next missile defense system (it had high capability at a low cost), so any alternative will be expensive. If the cost was the same, the ability will be greatly reduced.

On 18 December 2020, the government reviewed the plan to deploy two Aegis Ashore units and made a cabinet decision to procure two Aegis destroyers. On 31 August 2022, the Ministry of Defense included the cost of acquiring components for the construction of Aegis-equipped ships as part of the integrated missile and air defense capability, which was the main item in the budget request for FY2023. The Japanese Ministry of Defense proposed building a pair of ballistic missile defense ships at an estimated cost of 1 trillion yen ($7.1 billion). The Aegis system-equipped vessels were an alternative to the Aegis Ashore system, the purchase of which the government canceled in 2020. Officials were pushing to include the vessel's construction in the 2024 budget for it to be commissioned by the end of 2027. Defense Minister Yasukazu Hamada commented 02 September 2022 that the ASEVs were expected to be commissioned around March 2028 for the first vessel and March 2029 for the second vessel.

Although the construction cost had not been specified because the details of the request have not been finalized, it had been pointed out that the introduction cost may exceed Aegis Ashore's approximately 400 billion yen (estimate for two units). Regarding the introduction cost, it was estimated that it will be about 480 billion to 500 billion yen or more for two ships (240 billion to 250 billion yen or more per ship) in 2020. 　It had more advanced ballistic missile interception capabilities than existing Aegis destroyers and expandability to support hypersonic glide vehicles (HGVs).

At the time of the basic plan, there were three plans for the Aegis-equipped ship: a barge plan, a single-hull plan, and a multi-hull plan. To keep down construction costs, it was settled that the ships will be built using a typical single hull, according to several government sources. Mitsui had an LPD design which could be modified for increased deck space for VLS mounting. The other option was a traditional destroyer hull form based on either the Hyuga or Izumo hull since both were essentially enlarged destroyer hulls.