China's President Xi Jinping says there needs to be a peaceful resolution to the North Korean nuclear issue, urging all sides to avoid words or action that raise tensions during a phone call with Donald Trump .
Mr Xi's comments came as Pyongyang accused the US leader of driving the Korean peninsula to the brink of nuclear war.
The Pentagon said the United States and South Korea would proceed with a joint military exercise in 10 days.
China's foreign ministry said in a statement that Mr Xi told Mr Trump a peaceful resolution to the North Korean nuclear issue was essential, and urged calm.
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The White House added the relationship between Mr Trump and Mr Xi was "extremely close" and "will hopefully lead to a peaceful resolution of the North Korea problem."
Mr Trump, vacationing at his New Jersey golf resort earlier took to Twitter to warn North Korean leader Kim Jong-un that US "military solutions are now fully in place, locked and loaded, should North Korea act unwisely".
Despite the tough rhetoric, Mr Trump has insisted that "nobody loves a peaceful solution better than President Trump".
South Korea's presidential Blue House said in a statement on Saturday the United States and China were working to resolve the North Korea crisis.
Guam, the Pacific island that is a US territory and home to a US bases and around 6000 US military personnel, posted emergency guidelines on Friday to help residents prepare for any potential nuclear attack.
North Korean state news agency KCNA said on Thursday the North Korean army would complete plans in mid-August to fire four intermediate-range missiles over Japan to land in the sea 18 to 25 miles (30 to 40km) from Guam.
Japan's government decided to deploy its Patriot missile defence system to four locations in the west of the country, media reported.
Washington wants to stop Pyongyang from developing nuclear missiles that could hit the United States. North Korea sees its nuclear arsenal as protection against the United States and its partners in Asia.
Mr Trump said he did not want to talk about diplomatic "back channels" with North Korea after US media reports that Joseph Yun, the US envoy for North Korea policy, had engaged in diplomacy for several months with Pak Song Il, a senior diplomat at Pyongyang's UN mission, on the deteriorating ties and the issue of Americans imprisoned in North Korea.
Both Moscow and Berlin expressed alarm over the rise in rhetoric over North Korea.
President Emmanuel Macron and Mr Trump spoke on Saturday.
The White House said Mr Trump reiterated the US commitment to stop the "North Korean nuclear menace" and said Washington was ready with diplomatic, economic and military measures.
British Foreign Secretary Boris Johnson said blame for problems lay with North Korea, and that the international community was "shoulder to shoulder" in efforts to stop North Korean aggression.