Zhang Shengmin was promoted to the post in October after Beijing expelled his predecessor in another sweeping corruption purge. Both generals rank below Xi, who has held the CMC chairmanship since 2012. Liu, 61, is the chief of staff of the CMC's joint staff department, which oversees combat planning. Rumours of a probe swirled this week after Zhang Youxia and Liu appeared to miss an official meeting chaired by Xi and attended by second-ranked CMC vice chairman Zhang Shengmin.