A former senior official of the Maritime Self-Defense Force (MSDF) said that the government was thinking about converting the Izumo helicopter carrier into an aircraft carrier from the time it was in the basic design phase in the late 2000s. The official made the remark in connection with a plan by the Ministry of Defense (MOD) to convert the MSDF’s largest escort vessel for carrying helicopters into an aircraft carrier. The official also said that the government was considering using the renovated Izumo to defend the Nansei Islands, which are facing China’s growing maritime expansion
Funding to build the Izumo was allocated in the fiscal 2010 budget and the helicopter carrier was commissioned in 2015. With a flat flight deck extending from bow to stern like an aircraft carrier, it can carry many helicopters at once.
The basic design of the Izumo was done from 2006 to 2008, a period when Chinese public vessels were continuously invading Japanese waters around the Senkaku Islands. In 2008, Chinese military warships were spotted in the strait between the main island of Okinawa and Miyakojima Island for the first time.
According to multiple former senior MSDF officials, it was predicted that the Chinese military would gradually expand its activities in the East China Sea and thought that Japan’s aerial dominance would need to be secured. But the runway at the Air Self-Defense Force’s (ASDF) Naha Air Base is the only runway the SDF’s aircraft can use around Okinawa. The former senior MSDF official quoted above says, “We agreed to prepare for the possibility of not being able to use the Naha Air Base.”
Back then, the U.S. was developing stealth F-35B fighter jets, which are capable of taking off and landing vertically. The concept for the Izumo’s design was based on the assumption of using F-35B jets and new Osprey transport aircraft . The Izumo’s elevator connecting the deck with the hangar was designed to carry F-35B jets, which have a total length of about 15 meters and a total width of about 11 meters. Paint that can withstand the heat produced by F-35B jets when they land and take off was used on the Izumo. The senior official also said that the Izumo was intended to be renovated to attach a beveled board for the jets to take off from the deck.
The senior official said, “It goes without saying that the design takes into consideration changes that might occur several decades in the future. We thought that the political situation would determine whether it would actually be converted.”
“Offensive” aircraft carrier unconstitutional in gov’t view
Discussions have long been held on the possibility that possessing an “offensive” aircraft carrier would violate the “exclusive defense-oriented posture,” which is derived from Article 9 of the Constitution. Despite such discussions, the MSDF was steadily formulating a plan to build a warship with the possession of an aircraft carrier in mind.
Former senior MSDF officials say that the idea of possessing an escort ship designed to carry aircraft has been repeatedly considered since the late 1950s in the Cold War era, because Japan had to deal with the nuclear-powered submarines and long-range anti-ship missiles deployed by the former Soviet Union.
After the end of the Cold War, Japan’s escort vessels got bigger amid the expansion of the Self-Defense Forces’ (SDFs) overseas missions, such as disaster relief and transportation of Japanese citizens. The construction of the Hyuga escort vessel, which can carry a lot of large helicopters designed to transport goods and people, was approved in 2004. When the Izumo was built after the Hyuga, the idea of carrying fighter jets was studied amid rising tensions with China.
A former senior MSDF official says, “We were able to see that the situation in China would change drastically. The MSDF shared a common perception that we should give all possible consideration to operating fighter jets.” On the other hand, the senior official said that the MSDF “could not explain the plan publicly” because there is a government view that an “offensive” aircraft carrier is considered a form of military power forbidden under Article 9.
The idea of “converting the Izumo into an aircraft carrier” is re-emerging within the Defense Ministry ahead of the revisions of the National Defense Program Guidelines and the midterm defense buildup plan scheduled for the end of the year. People in the Defense Ministry are increasingly thinking that “using it to defend the Senkaku Islands would not be viewed as ‘offensive’.” More discussions will be necessary in light of this background.
