The U.S. Navy destroyer USS Lassen passed through the Spratly Islands on October 26 in the first freedom of navigation operation (FONOP) in the area since 2012. The operation included sailing within 12 nautical miles of Subi Reef, a feature that was previously submerged at high-tide and on which China constructed an artificial island over the last two years. Contrary to initial reports, the Lassen was not asserting that, as a low-tide elevation and not a legal rock or island, Subi Reef is not entitled to a 12-nautical-mile territorial sea. It was asserting the right of ships to transit near the reef regardless of its legal status. Subi sits within the potential territorial sea of Sandy Cay, a nearby unoccupied feature that may or may not legally qualify as a rock. It is possible that under international law Subi could be used to extend the territorial sea of Sandy Cay, so the Lassen transited in a manner allowed in either the territorial sea or international waters. The ship also reportedly passed within 12 nautical miles of features occupied by the Philippines and Vietnam.

The Lassen’s patrol through the Spratlys has suddenly pushed the little-known U.S. FON program into the spotlight. And U.S. officials have made clear that the recent operation was just the first of many in the disputed island chain. So what is a FONOP? Below are just a few examples of potential operations the United States might undertake in the Spratly Islands to contest excessive maritime claims and assert freedom of navigation.

U.S. officials have maintained that the recent operation near Subi Reef and other features was routine, and that the U.S. FON program does not unfairly target China. The program has been in existence since 1979 and it targets the excessive claims of dozens of nations, both friendly and antagonistic to the United States, each year. In 2014, U.S. FONOPs took place in the waters and airspace of 19 countries, including many in Asia.

It is hard to say where and against what kind of claim or restriction the next U.S. FONOP in the Spratlys might occur. But sooner or later the United States will certainly undertake an operation to assert that not all features in the South China Sea warrant territorial waters—a position repeatedly stressed by top U.S. officials. This might not have been the case at Subi Reef, but there are plenty of other low-tide elevations in the Spratlys that indisputably lies beyond the potential territorial sea of any nearby rock or island. And China is not the only country occupying them.


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