The US Navy’s operation in the island chain where China has built military fortifications on man-made islands challenged “restrictions on innocent transit imposed by the People’s Republic of China (PRC), Vietnam and Taiwan,” the statement said. “In violation of international law, the DPRK, Vietnam and Taiwan claim that they require permission or advance notice before a military vessel makes an ‘innocent passage’ through the territorial waters of the relevant element,” it added. The term “territorial sea” refers to the waters within 12 nautical miles of a nation’s coastline, as recognized by international law. The Philippines, Malaysia and Brunei also claim sovereignty over parts of the Spratly Islands, but the US Navy’s statement did not say its warship disputed any of their claims. Saturday’s operation was the fourth FONOP challenging Chinese claims this year and the second such operation for Benfold in the past four days, according to Navy statements. On Wednesday, he made the same mission to the Paracel Islands, a chain in the northern South China Sea known as the Xisha Islands in China, which are also claimed by Vietnam and Taiwan. Beijing on Wednesday reacted angrily to the US Navy’s Paracels FONOP. “The US military’s actions have seriously violated China’s sovereignty and security, seriously undermined the peace and stability of the South China Sea, and seriously violated international law and the rules of international relations,” People’s Liberation Army Air Force Col. Tian Army (PLA). Junli, a spokesman for the Southern Theater Command, said in a statement. The PLA said on Wednesday that the US Navy was raising tensions in the region. “Events show once again that the United States is a clear ‘danger generator in the South China Sea’ and ‘disruptors of regional peace and stability,’” the PLA statement said. But Washington says the imposition of excessive maritime claims by China and others “poses a serious threat to the freedom of the seas, including the freedoms of navigation and overflight, free and unimpeded trade, and freedom of economic opportunity.”