In 2012, China wrested control of Scarborough Shoal in the South China Sea from the Philippines. With the shoal—reefs, rocks, and a vast lagoon—located just 220 km (137 miles) from the Philippines’ main island Luzon, the incident heightened tensions and embarrassed Manila, which the following year opened a case in an international tribunal challenging Beijing’s territorial moves in the sea.
So alarm bells went off earlier this month when Chinese ships gathered at Sandy Cay, a set of sandbars close to Philippines-occupied Thitu Island in the sea’s Spratly archipelago. The island has a small civilian population and a decrepit runway the Philippines has been meaning to repair.