The United States Navy and Air Force, you may have noticed, have been taking some trips to the South China Sea recently.
Last month a guided missile destroyer, the USS Lassen, passed within 12 nautical miles of Subi Reef, an artificial island built atop a reef by Chinese engineers. This week it was a pair of B-52 bombers that flew over another artificial reef.
These movements are not accidental. They're being conducted to make a point about the rules of the game in international waters.