Rex Tillerson, right, and Jim Mattis appear at news conference following talks on Wednesday [Cliff Owen/AP]
The United States pressed China to exert more economic and diplomatic pressure on North Korea to help rein in its nuclear and missile programmes during a round of high-level talks in Washington.
The meeting on Wednesday of top US and Chinese diplomats and defence chiefs was held a day after President Donald Trump said Chinese efforts to use its leverage with Pyongyang had failed, raising fresh doubts about his administration's strategy for countering the threat from North Korea.
"We reiterated to China that they have a diplomatic responsibility to exert much greater economic and diplomatic pressure on the regime if they want to prevent further escalation in the region," US Secretary of State Rex Tillerson told reporters at a joint news conference with Defense Secretary Jim Mattis.
Mattis vowed to "continue to take necessary measures to defend ourselves and our allies" against North Korea, which is working to develop a nuclear-tipped missile capable of hitting the US.
But with the long-standing option of pre-emptive military