Equally important because of the threat of political and economic disputes are the sea lanes passing the Spratly Islands in the South China Sea. The U.S. Navy has long been assigned the mission of protecting the SLOCs of Southeast Asia. At present, events that could disrupt passage through the SE Asian sea lanes for an extended period are unlikely. Nevertheless, unanticipated challenges might cause sustained disruption with serious consequences. In principle, blockage of shipping lanes might not be a serious matter.
Alternate routes are available.
For example, ships denied access to the Malacca Straits might use Sunda. The Straits of Lombok and Makassar offer an alternative to the South China Sea. These detours are not so large, and after all, merchant vessels offer one of the cheapest modes of transport. In practice, however, it turns out that blockage of these SLOCs would matter a great deal. Nearly half the world fleet would be required to sail farther, generating a substantial increase in the requirement for vessel capacity.