China's president has warned the US and North Korea not to exacerbate tensions after Donald Trump said Kim Jong Un would "truly regret" military action.

Xi Jinping spoke to the US president by phone amid increasingly belligerent language over Pyongyang's suggestion that it was formulating a plan to fire missiles into the sea off the US territory of Guam.

"At present, the relevant parties must maintain restraint and avoid words and deeds that would exacerbate the tension on the Korean Peninsula," Mr Xi told Mr Trump, according to China's state-run CCTV.

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Earlier, at his Bedminster golf resort in New Jersey, Mr Trump told reporters: "I hope that they are going to fully understand the gravity of what I said, and what I said is what I mean.


"If he does anything with respect to Guam or anyplace else that's an American territory or an American ally, he will truly regret it and he will regret it fast."

He said that millions of Americans supported him because "finally we have a president that's sticking up for our nation and frankly sticking up for our friends and our allies".

Military solutions are now fully in place,locked and loaded,should North Korea act unwisely. Hopefully Kim Jong Un will find another path! — Donald J. Trump (@realDonaldTrump) August 11, 2017

On Twitter, he said the military was "locked and loaded" if North Korea carried out its threat.

He then called the Governor of Guam, Eddie Calvo, and assured him that the US military would "ensure the safety and security of the people of Guam, along with the rest of America".

The president also predicted the crisis could boost tourism "tenfold" for the US territory.

Mr Trump told Mr Calvo: "All over the world, they're talking about Guam, and they're talking about you, and I think tourism.

"I can say this, your tourism, you're going to go up like tenfold with the expenditure of no money, so I congratulate you ... It looks like a beautiful place."

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:: Why is North Korea threatening Guam?

Pyongyang, meanwhile, said nearly 3.5 million North Koreans had volunteered to join or rejoin the People's Army since the UN imposed new sanctions over its missile tests and nuclear ambitions.

The state-run KCNA news agency has previously accused the US president of driving the region "to the brink of nuclear war".

The White House said Mr Xi and Mr Trump "reiterated their mutual commitment to denuclearisation of the Korean Peninsula" and stressed their "extremely close relationship".

"President Trump and President Xi agreed North Korea must stop its provocative and escalatory behavior," a statement read.

Japan moves its PAC-3 Patriot missiles

German Chancellor Angela Merkel has also urged both sides to tone down their tough talk.

She said: "I don't see a military solution and I don't think it's called for.

"I think escalating the rhetoric is the wrong answer."

Mr Trump responded by saying: "Let her speak for Germany. She's certainly not referring to the United States."

Japan has begun deploying land-based Patriot interceptors at four cities, while American and South Korean officials said they planned to go ahead with military exercises later this month, which North Korea has described as a rehearsal for war.