the J-11B as powered by the WS-10 in 2014. Operational history In March 2011 a joint Sino-Pakistani exercise, Shaheen 1, was conducted at a Pakistan Air Force (PAF) base involving a contingent of Chinese aircraft and personnel from the PLAAF. Information on which aircraft were used by each side in the exercise was not released, but photos of Pakistani pilots inspecting what appeared to be Chinese Shenyang J-11B fighters were released on the internet. The exercise lasted for around 4 weeks and was the first time the PLAAF had deployed to and conducted "operational" aerial maneuvers in Pakistan with the PAF. P-8 interception On 19 August 2014 a J-11B intercepted a U.S. Navy P-8 Poseidon anti-submarine warfare aircraft that was over the South China Sea. The U.S. Department of Defense released details at a press conference on 22 August 2014 with Admiral John Kirby as spokesperson. According to Kirby, the incident occurred east of Hainan Island, in international airspace. The Chinese jet "crossed under the aircraft with one pass having only 50–100 feet [] separation. The Chinese jet also passed the nose of the P-8 at 90 degrees with its belly toward the P-8 Poseidon, believed to be displaying its weapons load-out. Afterwards, the J-11 flew directly under and alongside the P-8, bringing their wingtips, as I said, to within 20 feet []. And then conducted a roll over the P-8, passing within 45 feet []." He said the "unprofessional" and "unsafe" actions of the Chinese pilot was "not keeping with the kind of military-to-military relationship" the U.S. sought to establish with China. An official complaint was sent to China through regular diplomatic channels. The Pentagon commented further that: "Military activities may be conducted within the Exclusive Economic Zone of another nation as an exercise of the freedoms of navigation and overflight." In response, the Chinese Ministry of National Defense spokesman Yang Yujun said that the U.S. criticisms were "totally groundless" as the Chinese pilot professionally maintained a safe distance. Furthermore, he blamed the "massive and frequent close-in surveillance" by the U.S. as the root cause, and called for the end of surveillance flights to improve bilateral military ties. Variants J-11A (or J-11 with NATO reporting name Flanker-B) – Chinese/Russian assembled Su-27SK from Russian-made kits. 104 were built. J-11B (Flanker-L) – Chinese-developed variant with domestic subsystems. Block 02 powered by Shenyang WS-10 turbofan. J-11BS (Flanker-L+) – A twin-seat version of