Sukhoi Su-57 the Su-27. Extendible refueling probe is available to further increase its range. In the Su-57's design, Sukhoi addressed what it considered to be the F-22's limitations, such as its inability to use thrust vectoring to induce roll and yaw moments and a lack of space for weapons bays between the engines, and complications for stall recovery if thrust vectoring fails. The Su-57 will be the first operational aircraft in Russian Air Force service to use stealth technology. Similar to other stealth fighters such as the F-22, the airframe incorporates planform edge alignment to reduce its radar cross-section (RCS); the leading
Sukhoi Su-27 by the Japan Ministry of Defense. Russia denied the incursion, saying the jets were making routine flights near the disputed Kuril Islands. In another encounter, on 23 April 2014 an Su-27 nearly collided with a United States Air Force Boeing RC-135U over the Sea of Okhotsk. Russia plans to replace the Su-27 and the Mikoyan MiG-29 eventually with the Sukhoi Su-57 stealth fifth-generation multi-role twin-engine fighter. A squadron of Su-27SM3s was deployed to Syria in November 2015 as part of the Russian military intervention in the Syrian Civil War. Ethiopian Su-27s reportedly shot down two Eritrean MiG-29s and damaged another