Sukhoi/HAL FGFA Su-57, the foundation for FGFA's development, among many things the degree of low observability allowed by the design being the biggest of issues. However, Indian officials did not rule out the possibility of relaunching the FGFA project once the Su-57 is fully introduced into the Russian air force, or later acquiring the fully developed platform. On 19 August 2018, it was reported that the FGFA program was not cancelled; the President of the Russian United Aircraft Corporation said that is was just rumours, and that India was still working with Sukhoi on the FGFA program. Although there is no reliable
Sukhoi Su-15 the Su-15 was abruptly retired from the new Russian Air Force in 1993 to comply with the Treaty on Conventional Armed Forces in Europe. Most were hastily scrapped in favour of more advanced interceptors, including the Su-27 and MiG-31, but some are in reserve storage for emergency use. In Ukraine, the last Su-15s (at Kramatorsk and Belbek) were withdrawn from use in 1996. Some Western reports indicate that the Su-15TM was also designated Su-21 and the Su-15UM Su-21U. These reports are apparently incorrect. Designation Su-21 was reserved for Su-17M4 but never used. Sukhoi Su-15 The Sukhoi Su-15 (NATO reporting name: