President Donald Trump issued a new threat to North Korea on Friday, saying the US military was “locked and loaded” as Pyongyang accused him of driving the Korean peninsula to the brink of nuclear war and world powers expressed alarm.

The Pentagon said the United States and South Korea would proceed as planned with a joint military exercise in 10 days, an action sure to further antagonise North Korea.

China, Russia and Germany voiced dismay at the war of words between Pyongyang and Washington. Trump, who has pressed China to help rein in its ally North Korea, said he would speak to Chinese President Xi Jinping on Friday night.

In their telephone call, Xi told Trump the North Korean nuclear issue required a peaceful resolution through talks, and urged the “relevant side” to exercise restraint, avoiding words or action that raise tension, China's state media said.

Trump, vacationing at his Bedminster, New Jersey, golf resort, again referred to North Korea's leader in his latest bellicose remarks. “Military solutions are now fully in place, locked and loaded, should North Korea act unwisely,” he wrote on Twitter. “Hopefully Kim Jong Un will find another path!"

The term “locked and loaded,” popularised in the 1949 war film “Sands of Iwo Jima” starring American actor John Wayne, refers to preparations for shooting a gun.

Asked later by reporters to explain the remark, Trump said: "Those words are very, very easy to understand.”

Again referring to Kim, Trump added, “If he utters one threat ... or if he does anything with respect to Guam or any place else that's an American territory or an American ally, he will truly regret it, and he will regret it fast.”

In remarks to reporters after a meeting with US Secretary of State Rex Tillerson and US Ambassador to the United Nations Nikki Haley, Trump said the situation with North Korea was “very dangerous and it will not continue.”

“We will see what happens. We think that lots of good things could happen, and we could also have a bad solution,” he said.

Despite the tough rhetoric, Trump insisted that “nobody loves a peaceful solution better than President Trump.”

Trump said he thought US allies South Korea and Japan were "very happy” with how he was handling the confrontation.

The president, a wealthy businessman and former reality television personality, sent his tweet after North Korean state news agency, KCNA, said in a statement that “Trump is driving the situation on the Korean peninsula to the brink of a nuclear war.”

Guam, the Pacific island that is a U.S. territory, posted emergency guidelines on Friday to help residents prepare for any potential nuclear attack after a threat from North Korea to fire missiles in its vicinity.

Guam is home to a U.S. air base, a Navy installation, a Coast Guard group and roughly 6,000 U.S. military personnel. 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 18-25 miles (30-40 km) from Guam.

Trump called the governor of Guam, Eddie Baza Calvo. “We are with you a thousand percent. You are safe,” Trump told Calvo, who posted a video of him speaking with the president on Facebook.

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.

Trump said he was considering additional sanctions on North Korea, adding these would be “very strong.” He gave no details and did not make clear whether he meant unilateral or multilateral sanctions.

U.S. officials have said new U.S. steps that would target Chinese banks and firms doing business with Pyongyang are in the works, but these have appeared to be put on hold to give Beijing time to show it is serious about enforcing new U.N. sanctions.

'OVER THE TOP'

Trump said he did not want to talk about diplomatic “back channels” with North Korea after U.S. media reports that Joseph Yun, the U.S. envoy for North Korea policy, has engaged in diplomacy for several months with Pak Song Il, a senior diplomat at Pyongyang's U.N. mission, on the deteriorating relations and the issue of Americans imprisoned in North Korea.

But Daniel Russel, the former top U.S. diplomat for East Asia until April, said this so-called New York channel had been a relatively commonplace means of communication with North Korea over the years, and it was not a forum for negotiation.

“It's never been a vehicle for negotiations and this doesnt constitute substantive U.S.-DPRK dialogue,” he said, using the acronym for North Korea's formal name, Democratic People's Republic of Korea.

In Moscow, Russian Foreign Minister Sergei Lavrov urged Pyongyang and Washington to sign up to a previously unveiled joint Russian-Chinese plan under which North Korea would freeze missile tests and the United States and South Korea would impose a moratorium on large-scale military exercises. Neither the United States nor North Korea has embraced the plan.

Lavrov said the risks of a military conflict over North Korea's nuclear program are very high and Moscow is deeply worried by the threats from both sides.

“Unfortunately, the rhetoric in Washington and Pyongyang is now starting to go over the top,” Lavrov said on live state television at a forum for Russian students. “We still hope and believe that common sense will prevail.”

The annual joint U.S.-South Korean military exercise, called Ulchi-Freedom Guardian, is expected to proceed as scheduled starting on Aug. 21, said Lieutenant Colonel Christopher Logan, a Pentagon spokesman.

Trump's latest comments were a continuation of days of incendiary rhetoric, including his warning on Tuesday that the United States would unleash “fire and fury” on Pyongyang if it threatened the United States.

Amid the heated words, South Koreans are buying more ready-to-eat meals that could be used in an emergency and the government is going to expand nationwide civil defense drills planned for August 23. Hundreds of thousands of troops and huge arsenals are arrayed on both sides of the tense demilitarized zone between the two Koreas.

TRUMP RESPONDS TO MERKEL

Tension in the region rose when North Korea staged two nuclear bomb tests last year and increased further when it launched two intercontinental ballistic missile (ICBM) tests in July in defiance of world powers.

The United Nations this month tightened sanctions on Pyongyang after it tested two ICBMs designed to carry nuclear warheads to the United States.

The damage inflicted on world stocks this week by the tensions topped $1 trillion by Friday, as investors again took cover in the yen, the Swiss franc, gold and government bonds.

US financial markets took the increased rhetoric in stride. The Dow Jones Industrial Average rose 0.07 percent while the S&P 500 gained 0.13 percent and the Nasdaq Composite firmed 0.64 percent.

German Chancellor Angela Merkel said there is no military solution, adding that “an escalation of the rhetoric is the wrong answer.”

“I see the need for enduring work at the U.N. Security Council ... as well as tight cooperation between the countries involved, especially the U.S. and China,” she told reporters in Berlin.

Trump said hours later, “Let her speak for Germany.”

China, North Korea's most important trading partner, hopes all sides can do more to help ease the crisis and increase mutual trust, rather than taking turns in shows of strength, the Chinese Foreign Ministry said.

On Thursday, Trump reiterated complaints about the U.S. trade imbalance with China and said he would feel “differently" about the trade issue if China helped more on North Korea.