Satellite images obtained by Reuters on Thursday show a build-up of Chinese civilian vessels near contested Thitu Island, Manila¡¯s key outpost in the South China Sea, but a senior Philippine navy officer said they are ¡°not a cause for concern.¡±

One of the images taken by Maxar Technologies on Monday and reviewed by Reuters shows about 60 vessels, some within 2 nautical miles of Thitu ¡ª a strategically important island from which Manila monitors Chinese vessels and aircraft in the busy waterway.

Vice Adm. Alfonso Torres, chief of the Philippines¡¯ Western Command, said it was common for ¡°maritime militia¡± ships to gather in the area. Manila, the Pentagon and foreign diplomats say such vessels work with the Chinese coast guard and navy to strengthen Beijing¡¯s presence in disputed waters.