Hu Jintao's weak grip on China's army inspired Xi Jinping's military shake-up: sources

President Xi Jinping grew determined to shake up the army after he saw first-hand how his predecessor Hu Jintao was treated as a mere figurehead by his deputies, sources told the .

Xi, who became the Central Military Commission's third vice-chairman in 2010, witnessed how his fellow vice-chairmen Xu Caihou and Guo Boxiong took over the army's staff affairs right under Hu's nose, a military source said.

China watchers had long suspected Hu's grip on the army was weak. He succeeded former president Jiang Zemin as CMC chair only in 2004, two years after he took over from Jiang as party secretary. Even then, Jiang remained influential, installing his trusted aides Xu and Guo as Hu's deputies.

"Xu and Guo are Jiang's proxies. They left Hu isolated," a retired senior colonel said.

A source close to the People's Liberation Army's Academy of Military Sciences said: "Jiang continued to wield influence over military decisions through Xu and Guo."

Even the Americans came to doubt Hu's control. In 2011, the PLA conducted a surprise test flight of its first stealth fighter jet, the Jian-20, during then US defence minister Robert Gates' visit to Beijing. Gates saw that Hu was as stunned by the news as he was.