ballistic missile defense and amphibious landings. On 18 December 2018, Japan announced it will refit the Izumo-class destroyers to carry US-designed F-35B fighter jets. This makes them de facto aircraft carriers. To avoid controversy, the ruling parties call it a "multi-purpose operation destroyer". It would be the first such ship in the JMSDF since World War II. On 23 May 2019, retired MSDF vice-admiral Toshiyuki Ito stated that Japan requires at least four Izumo-class destroyers to be viable for real naval combat operations. He said "If you only have two vessels, you can only use them for training personnel for taking off and landing operations, so this plan doesn't make sense for MSDF officers, frankly speaking." As aircraft carriers, the Izumo-class destroyers are relatively small. Each ship can only carry approximately 10 F-35Bs. That is too few aircraft for effective air defense of a naval fleet. The Diet of Japan approved in 2019 the order of 42 STOVL Lockheed Martin F-35 Lightning II aircraft in addition to 135 F-35A model conventional takeoff and landing fighters for the Japanese Air Self Defense Force to operate from their land bases; the F-35B is same model aircraft that the US Marines operate from US Navy aircraft carriers and amphibious assault ships, the US Marines also plan to fly from the Japanese Izumo class after the STOVL modifications and refit. On October 14, 2020, the 3,000-ton submarine was unveiled. This is the first vessel of the Taigei class and the 22nd submarine vessel of the JMSDF. It will enter service in March 2022. On 30 June 2022, the Japan Ministry of Defense announced the construction of 12 offshore patrol vessels (OPVs) by Japan Marine United Corporation (JMU) for the Japanese Maritime Self-Defense Force (JMSDF) at a cost of ¥ 9 billion (US$66 million) per ship. The purpose of this OPV program is to provide enhanced maritime security, particularly around the southwestern Ryukyu Islands, including the disputed Senkaku/Diaoyu Islands in the East China Sea, by boosting JMSDF patrol activities in the region. These vessels are highly automated and configurable to meet a wide range of missions involving "enhanced steady-state intelligence, surveillance, and reconnaissance (ISR) in the waters around Japan". Under the contract, JMU is charged with delivering the 12 vessels to the JMSDF from fiscal year 2023, which starts on April 1, 2023. On August 31, 2022, the Japan Ministry of Defense announced that JMSDF