SINGAPORE - U.S. Defense Secretary Jim Mattis is calling North Korea a "clear and present danger" to the world.

Speaking at an international security conference in Singapore, Mattis says the North Koreans are increasing the pace and scope of their efforts to develop nuclear weapons and the long-range missiles to deliver them. He calls for international cooperation to de-nuclearize Korea.

Mattis notes what he calls China's renewed commitment to helping solve the North Korea problem. And he says he believes that ultimately, China will see North Korea as a liability.

Mattis is also reiterating U.S. objections to what he calls China's militarization of artificial islands in the South China Sea. But he also says conflict between China and the U.S. is not inevitable.