US Defence Secretary, James Mattis warned that Washington will not accept China's militarisation of man-made islands in the South China Sea. Speaking at a security conference in Singapore yesterday, he said such moves undermined regional stability. <br/><br/>Mr. Mattis said Washington oppose countries militarising artificial islands and enforcing excessive maritime claims. He said, US cannot and will not accept unilateral, coercive changes to the status quo. <br/><br/>China's territorial claims in the resource-rich South China Sea are contested by several nations.President Donald Trump and other senior US officials have repeatedly stated that America would protect its interests in the South China Sea, a key shipping route. <br/>Defence Secretary's comments came shortly after the UN Security Council had expanded targeted sanctions against North Korea in response to a series of missile tests conducted by Pyongyang this year.<br/><br/> The 15-member council voted unanimously to back the sanctions after weeks of negotiations between the US and China.