MANILA: The Philippine and Japanese navies held their first joint exercise on Friday in the South China Sea, as the two US allies boost security ties in the face of China's growing pressure.The drills followed the signing less than a month ago of an agreement between Manila and Tokyo to allow the deployment of troops on each other's territory.The Japanese destroyer JS Sazanami and the Philippine guided missile frigate BRP Jose Rizal took part in the two countries' first bilateral "Maritime Cooperative Activity", the Philippine military said in a statement.