 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.