SINGAPORE (AP) — U.S. Defense Secretary Jim Mattis on Saturday raised the prospect of additional American steps against China if its "militarization" of the South China Sea keeps apace. He said Beijing was intimidating and coercing others in the region by putting weapons systems on manmade islands. President Donald Trump, backing the remarks by his Pentagon chief at an international security forum in Singapore, said on Twitter: "Very surprised that China would be doing this?"