The People’s Liberation Army of China will participate in the exercise for the first time, sending ships that include the missile destroyer Haikou, the missile frigate Yueyang, the oiler Qiandaohu and the hospital ship Peace Ark. The Chinese were invited to join two years ago by Adm. Samuel Locklear, the chief of U.S. Pacific Command, and will do so now as Chinese President Xi Jinping pushes an overhaul and expansion of the Chinese military.