The senior ranks of the People's Liberation Army (PLA) are in tatters. The weekend purging of China's top general, Zhang Youxia, and another senior military officer, Gen Liu Zhenli, has left serious questions about what triggered the elite power struggles unfolding in the country - and what this means for China's warfighting capacity, whether it be any ambition to take Taiwan by force or engage in another major regional conflict. Zhang, 75, was vice-chairman of the Central Military Commission (