Defense Chief Ash Carter said at an international security conference in Singapore on Saturday that China’s military activity in the South China Sea could lead to a “great wall of self-isolation.”
"There is growing anxiety in this region, and in this room, about China's activities on the seas, in cyberspace, and in the region's airspace," he said. "Indeed, in the South China Sea, China has taken some expansive and unprecedented actions, that have generated concerns about China's strategic intentions."
Carter also called an upcoming ruling by a U.N. arbitration tribunal on the Philippines’ challenge to China claims in the contested region “an opportunity for China and the rest of the region to recommit to a principled future to renewed diplomacy, and lowering tensions, rather than raising them.”
Carter also defended the importance to exercise its right to fly and sail small military aircraft and ships near other countries’ coasts, including China’s, in a question-and-answer session with the audience.
"What we stand for is the principle of rule of law and abiding by international law in the commons," Carter said. "It's not a focus on China. It's a focus on principle."
Meanwhile, Carter said a security network would represent “the next wave” in Asia-Pacific security.
"It is inclusive, since any nation and any military - no matter its capability, budget, or experience - can contribute. Everyone gets a voice, no one is excluded, and hopefully, no one excludes themselves," he said, alluding to China.
He emphasized possibilities for cooperating with China while stating that the U.S. will remain the pre-eminent power.
"America wants to expand military-to-military agreements with China to focus not only on risk reduction, but also on practical cooperation. Our two militaries can also work together," he said, bilaterally or as part of a broader security network to combat global threats like terrorism and piracy.
Tom Mahnken, president of the Center for Strategic and Budgetary Assessments, a Washington think tank, praised Carter's emphasis on developing partnerships.
"Secretary Carter was right to emphasize multilateral approaches in the Asia-Pacific region. Indeed, America's alliances and partnerships in the region give us an enduring competitive advantage," Mahnken said by email from Washington. "By contrast, China's actions have increasingly isolated it."
At a news conference later, Adm. Harry Harris, head of U.S. Pacific Command, said that while his forces are ready to confront China if necessary, there have been few significant issues with China lately in the South China Sea.
"We've seen positive behavior in the last several months by China," Harris said, adding, "I'm encouraged by the activities" between the U.S. and Chinese militaries. He noted that China plans to attend the Rim of the Pacific exercise this year, with U.S. and Chinese warships operating together from Guam to Hawaii.
Adm. John Richardson, the Navy's top admiral, said "more and more" interactions at sea with the Chinese navy are safe and professional.
In Carter’s speech, he asserted that the U.S. intends to maintain its military presence in the Asia-Pacific.
"The Defense Department maintains its world-leading capabilities because the United States has made incomparable investments in it over decades. As a result, it will take decades or more for anyone to build the kind of military capability the United States possesses," he said.
China did not send its defense minister to Singapore, and Carter held no meetings with members of Beijing's delegation. But at a conference-opening dinner Friday evening Carter shook hands and spoke briefly with the senior Chinese representative, Adm. Sun Jianguo, according to a U.S. official who was present.
The Associated Press contributed to this report.