A US warship sailed within 12 nautical miles of one of China's man-made islands in South China Sea on Tuesday in the most significant US challenge yet to territorial limits Beijing claims around the Spratly archipelago.
The move triggered an angry rebuke from Beijing and a warning that a minor incident in the area, which is one of the world's busiest sea lanes, could spark war if the United States did not stop what it called "provocative acts."
"The attention to disputed claims in the South China Sea, the prominence of those disputes, is having the effect of causing many countries in the region to want to intensify their security cooperation with the United States," US Defense Secretary Ash Carter told reporters on his way to South Korea.
Carter said discussions at an upcoming defense summit in Malaysia would include developments in the South China Sea, "the most notable of which in the last year has been the unprecedented rate of dredging and military activity by China."
Carter is due to arrive in Seoul later today and is scheduled to hold talks with South Korea's defence chief on Monday, focused on the allies' response to North Korea's nuclear and missile programmes.
He later flies to Malaysia for the meeting of Southeast Asia defence ministers, which China's Defence Minister Chang Wanquan is also due to attend.