Over the past five years, no country in Southeast Asia has challenged China’s regional strategic ambitions more assertively than Vietnam. Repeatedly standing up to Beijing’s aims in the South China Sea, Vietnam has attempted to allow foreign oil exploration in disputed maritime areas and, like China, built up the submerged reefs, small islets and banks it occupies and added installations, though on a much smaller scale. It has, at times, tried to work with its neighbors, such as the Philippines under former President Benigno Aquino III, to highlight what it sees as China’s illegal behavior in the South China Sea. […]