It is believed that Putin sold China Russia’s top submarine in exchange for economic gains to ease the effect of Western sanctions. That is a natural belief as people always focuses on past enmity between Russia and China due to Mao’s fight against Soviet revisionism for leadership of the socialist camp of the Cold War, which led to border conflict.
http://chinadailymail.com/2014/10/2...-as-russia-seeks-to-avoid-economic-recession/
http://chinadailymail.com/2014/10/2...-as-russia-seeks-to-avoid-economic-recession/