The amount of military facilities China builds on islands in the South China Sea depends on the level of threat it faces although China does not seek militarization, the navy chief told his U.S. counterpart Wednesday.

Every year more than $5 trillion of world trade is shipped through the South China Sea, believed to have huge deposits of oil and gas, which China claims almost entirely. Brunei, Malaysia, the Philippines, Taiwan and Vietnam have rival claims.

China has been reclaiming land and building artificial islands there that it says are mostly for civilian uses but are also for defensive purposes.