During a visit to Japan at the start of an Asian tour, Secretary of State Rex Tillerson said he would urge China to play its part in reining in its neighbor.
In his first foray into crisis diplomacy, the new US envoy wants to reassure key Asian allies that Washington stands with them in the face of the accelerating nuclear and missile threats. But he warned that past policies and punishments have had virtually no effect on Pyongyang's ambitions.
"I think it's important to recognize that the diplomatic and other efforts of the past 20 years to bring North Korea to a point of denuclearization have failed," he told a press conference with Japan's Foreign Minister Fumio Kishida.
North Korea last week test fired a salvo of ballistic missiles that fell in waters off Japan.
"In the face of the ever-escalating threat it is clear that a new approach is required," Tillerson said, offering no details.
But he reiterated Washington's vow to face down the North Korean threat and back regional friends Japan and South Korea.