The South China Sea is a strategic waterway with overlapping territorial claims from several countries. An air defense identification zone (ADIZ) is airspace over international waters that a country claims the right to monitor and control for national security purposes. Tensions are rising as China's actions in the region are perceived as increasingly aggressive. - Philippine Defense Secretary Gilberto Teodoro stated that the Philippines and its allies would take action against China if it attempts to impose an air defense zone over the South China Sea. - The warning follows confrontations between Chinese aircraft and those of the Philippines, Australia, and the United States. - Teodoro emphasized the threat to national and global security posed by China's potential restrictions on freedom of flights. - The Philippines is working with its allies to ensure freedom of navigation and overflight in the South China Sea.