The United States pressed China to exert more economic and diplomatic pressure on North Korea to help rein in its nuclear and missile programs during a round of high-level talks in Washington on Wednesday.

The meeting of top U.S. and Chinese diplomats and defense chiefs was held a day after President Donald Trump said China's efforts to use its leverage with Pyongyang had failed, raising fresh doubts about his administration's strategy for countering the threat from North Korea.

The death of American university student Otto Warmbier this week, after his release from 17 months of imprisonment in Pyongyang, has further complicated Trump's approach to North Korea, his top national security challenge.