SINGAPORE - US Defence Secretary Ashton Carter arrived in Singapore on Thursday (June 2) ahead of a regional security summit likely to be dominated by China's continued military build up in the South China Sea.
His attendance at this weekend's Shangri-La Dialogue is part of a broader US diplomatic push to build and maintain alliances in the Asia-Pacific region, which America sees as key to its own long-term economic and security interests.
In the year since the last summit, China has stepped up its maritime patrols across the South China Sea and built up a series of military bases on small islands it reclaimed from the ocean.
Carter has spoken forcefully about China's military moves in the South China Sea and last week said Beijing risked building a "Great Wall of self-isolation."
There are no official US-China meetings planned at the Shangri-La meeting, at which Carter gives a keynote speech on Saturday.
China has indicated it may soon declare an Air Defence Identification Zone (ADIZ) that would require civilian aircraft to identify themselves to military controllers in the region. Beijing did something similar in the East China Sea two years ago over several small islands contested by Japan.
"We of course would be very concerned about a Chinese declaration of an ADIZ," a US defence official said, speaking on condition of anonymity.
"The declaration of an ADIZ over disputed territory is provocative," the official added, but noted: "such a declaration would not affect our own military operations." The US military has conducted several "freedom of navigation" operations in which it sends a ship or plane to pass by a Chinese-claimed island as a way of showing it rejects claims of sovereignty.
Washington has stressed the importance of increased ties to regional partners such as Vietnam and Malaysia as a counterbalance to China's moves.
But incoming Philippine leader Rodrigo Duterte said Tuesday he would not be fully reliant on the United States, the Philippines' former colonial ruler and most important military ally.
And in a sign of a possibly warming view of China, Duterte called Xi Jinping "a great president".
Chinese-Philippine ties soured during the six-year term of outgoing President Benigno Aquino, whose government sued China before a United Nations tribunal over its claims to most of the South China Sea.
The Philippines has "a new government there and we look forward to working with them, talking with them about our alliance, about security affairs in the region, and I very much look forward to meeting my new counterpart," Carter told reporters as he flew to Singapore, adding that the US-Philippines alliance was "ironclad."
Carter's Singapore visit is the fifth time he has travelled to the Asia-Pacific region since becoming Pentagon chief in February 2015, calling it "the single most consequential" region for America's future.