The head of the U.S. Indo-Pacific Command said the United States and its allies need to operate with a greater sense of urgency amid rising tensions and China’s increasingly assertive military actions. Adm. John C. Aquilino said the U.S. and its allies need to work together more frequently in international waters to build interoperability so they can operate together quickly if needed. China claims virtually the entire South China Sea and has transformed seven shoals into missile-protected island bases.