latter period of 1981, the first F-15J/DJ aircraft were sent to 202nd Tactical Fighter Squadron, which was reorganized as an Eagle FTU and renamed the 23 Flying Training Squadron at Nyutabaru base on 21 December 1982. The JASDF developed a plan to form the first squadron after the KAL007 shootdown by a Soviet Su-15 on 1 September 1983. In March 1984, new F-15Js began replacing the 203rd Tactical Fighter Squadron's F-104Js at Chitose Air Base, located across the La Pérouse Strait from the Soviet fighter base on Sakhalin Island. On , it was announced that Japan is considering selling their F-15s to the U.S. in order to acquire funds to purchase F-35s. The Japanese Ministry of Defense confirmed on February 4, 2022 that 68F-15Js will be upgraded through the Japan Super Interceptor (JSI) programme under a cost of JPY646.5 billion (USD5.6 billion). Boeing was awarded an undefinitized contract not-to-exceed $24,550,000 for the F-15 Japan Super Interceptor program. Design F-15J/DJs are identical to F-15C/Ds aside from the ECM, radar warning system, and nuclear equipment. The AN/ALQ-135 Internal Countermeasures System is replaced by the indigenous J/ALQ-8 and the AN/ALR-56 Radar Warning Receiver is replaced by the J/APR-4. The engine is the Pratt & Whitney F100 turbofan, produced under license by IHI Corporation. Some aircraft still have an inertial measurement unit, an old type of the Inertial navigation system. All F-15J/DJs have two UHF radios, which are also VHF capable. The F-15J is characterized by an indigenous data link, but they do not support Link 16 FDL mounted by USAF F-15Cs. It works as a basic bidirectional link with the Japanese ground-controlled intercept network, and it is limited because it is not a true network. Mitsubishi received the F-15C/D Multistage Improvement Program (MSIP) and in 1987 began upgrading the F-15J/DJs. Improvements included an uprated central computer, engines, armament control set and added the J/APQ-1 countermeasures set. The F100-PW-220 (IHI-220) was upgraded to the F100-PW-220E (IHI-220E) with a digital engine electronic control retrofit. Differences in appearance from earlier F-15Js include the J/ALQ-8 ICS with an ICS antenna mounted under the intake. The J/APQ-4 RWR antenna position on the F-15J/DJs is the same as F-15C/Ds, but the lens of F-15J/DJ MSIPs is black rather than white for F-15C/Ds. Improvements and upgrades F-15Js have been equipped with the Japanese-built AAM-3 missile, an improved AIM-9 Sidewinder follow-on with distinctive "barbed" forward fins. Japan has been investigating an