In September, David Shear, assistant secretary of defense for Asia-Pacific security, told the Senate Armed Services Committee that the U.S. Navy hadn't steamed or flown within 12 nautical miles of the islands since 2012, which is before China's island construction project began in earnest. Six nations with South China Sea coasts have competing claims to the territory being staked out by China's island building.
Later that day, House Armed Services Committee member Randy Forbes, R-Va. sent a letter signed by a bipartisan group of 29 House members calling the island-building project a threat to freedom of navigation and the peaceful international order in place since the end of World War II.
"In order to deter these actions and prevent further erosion of stability in the region, the United States must make clear that it is fully committed to maintaining freedom of navigation in the South China Sea," the letter read, calling for a "highly symbolic" passage of Navy ships and aircraft past the islands to send a message to China.
When reports that the U.S. was planning to challenge China's island claims surfaced in May, a Chinese foreign ministry spokesperson urged "relevant countries to refrain from taking risky and provocative action," according to a report in the Wall Street Journal.
Bryan Clark, a retired submarine officer and analyst with the Center for Strategic and Budgetary Assessments, said that passage through territorial waters is a routine Navy operation typically used to build a legal case under international law for freedom of navigation in international waters, and right of innocent passage within territorial waters.
Innocent passage, the right of a state to pass through the territorial waters of another, is usually conducted with little fanfare. But what makes the planned passage through China's newly claimed territorial waters significant is that the administration had previously prohibited the Navy from doing it in the Spratly Islands, Clark said.
"If you act like they have a legal 12-mile limit, even though the U.S. has said it doesn't recognize it, you are tacitly acknowledging those claims as legitimate," Clark said, adding that even if the claims were legitimate, the U.S. would have the right to pass through under the right of innocent passage.
The Chinese government claimed the same right when its navy's ships passed within 12 nautical miles of the U.S.-held Aleutian Islands off Alaska In September, after a joint exercise with the Russian military.
The U.S. and China's neighbors in the region are concerned that China is creating military installations on the islands. In June, images surfaced of a nearly complete 10,000-foot-long airstrip on one of the islands, big enough to accommodate military aircraft.
China claims nearly all of the South China Sea, a position that has put it at loggerheads with its neighbors and prompted countries in the region, including erstwhile enemies such as Vietnam, to turn to the U.S. to offset the newly aggressive China.
China's actions have also prompted renewed military-to-military relations with the Philippines, more than two decades after the U.S. was kicked out of the country following a wave of anti-American sentiment inside the former U.S. colony.
An agreement signed last year that allows U.S. forces to use Philippine military facilities has been a signature accomplishment in the Obama administration's strategic pivot to Asia.