By Hannah Parry
China will intervene if America attacks North Korea first, according to a state-owned paper, and will only stay neutral if Kim Jong-un attacks the US first.
An editorial in the Global Times, warned that "China should also make clear that if North Korea launches missiles that threaten US soil first and the US retaliates, China will stay neutral," the Daily Mail reported.
"If the US and South Korea carry out strikes and try to overthrow the North Korean regime and change the political pattern of the Korean Peninsula, China will prevent them from doing so."
China also expressed its "strong dissatisfaction" with the US Navy over its operations in the South China Sea.
The warning comes amid escalating tensions between the US and North Korea.
Pyongyang has warned it plans to launch a nuclear strike on Guam after President Trump announced that any more threats against the US would be met with "fire and fury".
Pentagon chief James Mattis issued his own warning among the increasingly aggressive rhetoric, telling Kim Jong-un that he risks destroying his regime and his people if he attacks.
Today, Trump ratcheted up his rhetoric towards Jong-un, warning Pyongyang against attacking Guam or US allies.
The magnitude of the nuclear crisis was underlined as one White House aide, Sebastian Gorka, compared it to the Cuban Missile Crisis.
China, North Korea's most important ally and trading partner, has reiterated calls for calm during the current crisis.
It has expressed frustration with both Pyongyang's repeated nuclear and missile tests and with behavior from South Korea and the United States that it sees as escalating tensions.
The widely read state-run Times, published by the ruling Communist Party's official People's Daily, wrote in an editorial that Beijing is not able to persuade either Washington or Pyongyang to back down.
"If the U.S. and South Korea carry out strikes and try to overthrow the North Korean regime and change the political pattern of the Korean Peninsula, China will prevent them from doing so."
China has long worried that any conflict on the Korean peninsula, or a repeat of the 1950-53 Korean war, could unleash a wave of destabilising refugees into its northeast, and could end up with a reunified county allied with the United States.
North Korea is a useful buffer state for China between it and US forces based in South Korea, and also across the sea in Japan.
The Global Times said China will "firmly resist any side which wants to change the status quo of the areas where China's interests are concerned".
"The Korean Peninsula is where the strategic interests of all sides converge, and no side should try to be the absolute dominator of the region."
Amid heightened tensions in the region, Beijing staged "large-scale" military exercises with dozens of ships, fighter jets and submarines adjacent to the Korean Peninsula on Monday - just months after moving 150,000 troops to its border with North Korea.
Calling the situation on the Korean Peninsula "complicated and sensitive", China's foreign ministry issued a statement warning that parties involved in the impasse should avoid "words and actions that escalate the situation".
Russia, meanwhile, moved military equipment including helicopters and combat vehicles to its southern frontier with the hermit state earlier this year. Moscow has displayed its own frightening military strength at a war games event in Siberia this week and during a vast Navy Day parade in Vladivostok - about 100 miles from North Korean territory.
Germany urged both North Korea and the United States to show "restraint" in their mounting war of words.
"We are watching the increasing rhetorical escalation regarding the Korean Peninsula with the greatest concern," foreign ministry spokesman Martin Schaefer told reporters. "That is why we call on all sides to use restraint."
Schaefer said Berlin was convinced a "military option" could not be "the answer in the quest for a nuclear weapon-free Southeast Asia".
He urged the international community to "thoroughly implement" the latest round of sanctions against North Korea approved by the United Nations Security Council and backed a call by Tillerson to resume talks with Pyongyang if it halts ballistic missile tests.
"We must all continue our diplomatic efforts - it is the only way to ensure that the threat of the illegal North Korean nuclear weapons programme can be contained," he said.
However, the US would not be alone if it did decide to strike first.
Australia "will come to the aid of the United States" if North Korea attacks, Prime Minister Malcolm Turnbull said, after Pyongyang outlined its plans to fire missiles near the US territory of Guam.
The Australian leader's comments of support to close ally Washington followed President Donald Trump's warning to North Korea that it should be "very, very nervous" of the consequences if the isolated nation even thought of attacking US soil.
"The United States has no stronger ally than Australia," Turnbull told Melbourne commercial radio station 3AW. "And we have an ANZUS agreement and if there is an attack on Australia or the United States then... each of us will come to the other's aid.
"So let's be very clear about that. If there is an attack on the United States by North Korea, then the ANZUS treaty will be invoked and Australia will come to the aid of the United States."
The European Union said tensions over North Korea can only be resolved by peaceful means, with foreign policy chief Federica Mogherini's spokeswoman saying the developments are "of great concern to the EU".
Relations between Washington and Pyongyang have been tense for months, in the wake of the North's repeated missile tests, including two successful intercontinental ballistic missile (ICBM) test launches in July.
The escalating dispute took an unexpected turn Tuesday when Trump seemed to borrow from the North's arsenal of rhetoric and said it faced "fire and fury like the world has never seen" if it continued to threaten the US.
Trump himself fired another flare in Kim Jong-Un's direction on Wednesday morning, saying in tweets the United States' nuclear arsenal is "stronger and more powerful than ever before" and he "hopefully" won't need to use it.
"My first order as President was to renovate and modernise our nuclear arsenal. It is now far stronger and more powerful than ever before," Trump said. "Hopefully we will never have to use this power, but there will never be a time that we are not the most powerful nation in the world!"
Trump made the show of might on social media after his secretary of state, Rex Tillerson, tried to dial down the conflict as he returned to Washington from Southeast Asia on a trip that included a pit stop in Guam.
Guam, which is roughly 3424km from North Korea, is home to both Andersen Air Force Base and Naval Base Guam housing thousands of American service members and their families.
Roughly 28 per cent of the island is occupied by the US military. The base houses bomber assurance and deterrence missions, including six B-52s which the air force says provide "strategic global strike capability [to] deter potential adversaries and provide reassurance to allies" and that they are ready to go.
North Korea has said it could carry out a pre-emptive operation if the US showed signs of provocation.
Tillerson said Trump's "fire and fury" charge to Kim shouldn't have Americans panicking because North Korea does not pose an 'imminent threat' to the United States.
Pyongyang's volatile dictator has warned that he was "carefully examining" plans to make "an enveloping fire" around Guam, which is home to about 163,000 people and a sprawling American military base.
The UN Security Council on Saturday approved tough sanctions which could cost Pyongyang US$1 billion a year, with the sweeping measures the first of that scope to be imposed on North Korea since Trump took office.
Meanwhile, China expressed its "strong dissatisfaction" with the US over the Navy's latest freedom of navigation operation in which a warship sailed past one of China's man-made islands in the strategic South China Sea.
Foreign Ministry spokesman Geng Shuang said in a statement late Thursday that the US move "severely undermines China's sovereignty and security, and severely endangers the safety of frontline personnel of both sides."
China, which claims virtually the entire South China Sea, routinely protests such operations, which President Donald Trump's administration has continued partly to reassure allies locked in territorial disputes with Beijing.
"China has the firm determination to safeguard its territorial sovereignty and maritime interests," Geng said.
The US move will "compel China to take measures to further raise its capacity to defend national territory," he said.
A US Navy official told The Associated Press that the destroyer USS John S. McCain sailed past Mischief Reef on Thursday but gave no details.
US officials say the military will continue to sail, fly and operate wherever permitted by international law.
Geng said the Chinese navy "identified the US warship, warned and expelled it."
China and the US maintain different interpretations on international law as applied to the operation of warships, and Beijing has ignored a Hague arbitration court's ruling that invalidated much of its South China Sea claim.
Tensions escalated after China began to build seven reefs, including Mischief, into islands, including three with runways, which the US and China's neighbors fear could be used to project Beijing's military might and potentially obstruct freedom of navigation.
China has reportedly installed a missile defense system on the new islands, although Foreign Minister Wang Yi said Monday that China had "stopped or already completed land reclamation," on the islands two years ago.
Earlier, Wang said talks on a nonaggression pact aimed at preventing clashes from erupting in the South China Sea may start this year if "outside parties" don't cause a major disruption, in an apparent reference to Washington and allies such as Japan.
The US is not a party to the disputes in the busy and potentially oil- and gas-rich waters that also involve Brunei, Malaysia, the Philippines, Taiwan and Vietnam.
Washington, however, has declared it in its interest to ensure that the conflicts are resolved peacefully and that freedom of navigation and overflight remain unhampered.
An estimated $5 trillion in annual trade passes through the waterway.
Washington's critical actions came as it courts the help of China, North Korea's ally, in taming Pyongyang's nuclear weapons ambitions and ending its missile tests.
- additional reporting AP
The Fed held rates steady at 4.25%-4.50% for the fourth meeting in a row.