WASHINGTON (AFP) - United States President Donald Trump will speak by telephone with the leaders of China and Japan on Sunday (July 2), in talks likely to be dominated by North Korea's nuclear drive and the threats posed by its belligerent leadership.

The Trump administration has been growing increasingly exasperated with North Korean leader Kim Jong Un's regime, which has staged a barrage of missile tests in recent months.

Trump had been pinning his hopes on China - North Korea's main diplomatic ally - to bring pressure to bear on Pyongyang, but declared last week that their efforts had failed.

He has presented sanctions as the best way to proceed with the hermit state, opting for that approach over dialogue with the regime.

On Sunday, Trump will speak with Chinese President Xi Jinping at 8.45pm (8.45am Monday Singapore time) and with Japanese Prime Minister Shinzo Abe at 8pm.

During talks with South Korean leader Moon Jae In - who has pushed for a policy of engagement with Pyongyang - on Friday, Trump called for a "determined response" to the North.

But the pair failed to map out a joint strategy on how to respond to North Korean threats.

"The era of strategic patience with the North Korean regime has failed, many years it has failed. Frankly, that patience is over," Trump said.

There was also deep anger in the United States after Otto Warmbier, an American student who was detained in North Korea on a tourist trip around 18 months ago, was returned home in a coma earlier this month. He died several days later.