In situations where no images were found, we substituted other islands into the study set and searched the archives again. Since published aerial photos and media reports indicated that island activities and infrastructure were small-scale and rudimentary, the imagery with the highest spatial detail had the best chance of providing observable evidence of island occupations. 19 Table 1 shows the initial set of islands that were selected for detailed examination. The table gives the geographic location of each island and explains why each was selected for image analysis. Every island that was chosen for detailed study was either a significant base of operations or a flashpoint with a documented history of threats and conflict between two or more countries.
Aerial photos indicate that China constructed several octagonal structures on the reef.
Philippines, Taiwan, and Vietnam also have claims to the reef. The island reportedly has an airstrip, lighthouse, and power plant. 20 China, Taiwan, and Vietnam also have claims to the island. This island is one of the larger land masses in the area. It reportedly has a marine garrison, helicopter pad, meteorological center, and power plant.