US Defense Secretary slammed China for building up military presence on artificial South China Sea islands and threatening Taiwan.
"Despite China’s claims to the contrary, the placement of these weapon systems is tied directly to the military use for the purposes of intimidation and coercion," he said Saturday at an annual security summit in Singapore.
He noted however, that cooperation with China was "welcome when possible," promising to travel to Beijing soon as part of Washington's "constructive, results-oriented" cooperation strategy with China.
"So make no mistake, America is in the Indo-Pacific to stay," the secretary said at Shangri-La Dialogue summit.
Mattis stressed no one nation should dominate Indo-Pacific and called sea lanes "arteries of economic vitality for all," in a thinly-veiled warning to China.
Speaking at the summit, Mattis also noted that the United States had a history of cooperating with both Russia and China and stressed they should be able to overcome their differences.