Opinion | As US-backed Philippines asserts itself against China, war games risk heating tensions at sea

US Marines joined Filipino counterparts on May 5 for a mock battle at a telling location: a small, remote territory just 100 miles (161km) off the southern tip of the contested island of Taiwan.

The combat drill is part of the week-long Balikatan military exercise that has brought together naval, air and ground forces of the Philippines and the United States, with Australia and France also joining some manoeuvres.

With the “maritime strike” on Wednesday in which a decommissioned ship was sunk and exercises at repelling an advancing foreign army were conducted, the aim is to display a united front against China, which Washington and Manila perceive as a threat to the region. Balikatan is Tagalog for “shoulder to shoulder.”

Joint Philippines-US naval drills have become an annual event. But as an expert in international relations, I believe this year’s drills mark an inflection point in the regional politics of the South China Sea.

For the first time, warships taking part in the exercise ventured outside the 12 nautical-mile boundary that demarcates the territorial waters of the Philippines. This extends military operations into the grey area where the Philippines’ exclusive economic zone rubs up against the territory claimed by China and designated by its “nine-dash line”.

The South China Sea has long been the source of maritime disputes between China, which claims the vast majority of its waters, and nations including Vietnam, the Philippines, Malaysia and Indonesia. In addition, heightened tensions over the status of Taiwan – a territory that the Biden administration has pledged to defend militarily in the event of a Chinese invasion – have made the South China Sea even more strategically important.