“However, all something like that will do is act as a further irritant to China, whose position is that this is their backyard, much as the same way as the U.S. would treat the Gulf of Mexico, for instance,” he added.

In a show of strength, a U.S. Navy destroyer came within 12 nautical miles of Triton Island in the Paracels chain last month. The Pentagon claimed that the maneuver was designed to maintain freedom of navigation.

Beijing has repeatedly claimed that it opposes the militarization of the South China Sea, but that it would still set up defensive positions. A State Department spokesman said: “While I cannot comment on matters related to intelligence, we do watch these matters very closely. The United States continues to call on all claimants to halt land reclamation, construction, and militarization of features in the South China Sea.”