WASHINGTON (Dispatches) -- U.S. President Donald Trump on Friday said a military option against North Korea was "locked and loaded," his latest salvo in an escalating war of words with Pyongyang.
"Military solutions are now fully in place, locked and loaded, should North Korea act unwisely. Hopefully Kim Jong Un will find another path!" Trump tweeted.
The U.S. president's Twitter missive ratcheted up his already bellicose rhetoric with Kim over North Korea's weapons program, as Beijing appealed to the two leaders to dampen their fiery exchange.
A day prior Trump had hardened his warning that Pyongyang would face "fire and fury" if it kept threatening the United States, saying maybe his tough talk "wasn't tough enough."
Trump also warned North Korea it should be "very, very nervous" of the consequences if it even thinks of attacking U.S. soil, after Pyongyang said it was readying plans to launch missiles towards the Pacific territory of Guam.
Pyongyang said the scheme to target the island, a key U.S. military outpost in the western Pacific, was intended to "signal a crucial warning" as "only absolute force" would have an effect on a U.S. leader "bereft of reason."
Beijing on Friday pleaded with the U.S. and North Korea for restraint, urging the two parties "to be cautious with their words and actions."
China has repeatedly urged a resumption of long-dormant six-party talks to peacefully resolve the crisis, but its position has been overshadowed by the emerging brinkmanship between Trump and Kim.
A Chinese state-run newspaper said on Friday China should remain neutral if North Korea launches an attack on Guam.
"China should also make clear that if North Korea launches missiles that threaten U.S. soil first and the U.S. retaliates, China will stay neutral," the Global Times, which is widely read but does not represent government policy, said in an editorial.
"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," it said.
North Korea's state-run KCNA news agency said on Thursday its army would complete plans in mid-August to fire four intermediate-range missiles over Japan to land near Guam.
Trump said the North Korean leader was not going to get away with his "horrific" comments and disrespecting America.
"Let's see what he does with Guam. He does something in Guam, it will be an event the likes of which nobody's seen before, what will happen in North Korea," Trump told reporters in New Jersey, without offering specifics.
Shortly after Trump spoke, U.S. Defense Secretary James Mattis told reporters the United States still preferred a diplomatic approach to the North Korean threat and a war would be "catastrophic."
Asked if the United States was ready if North Korea made a hostile act, he said: "We are ready."
The North staged two nuclear bomb tests last year and launched two intercontinental ballistic missile tests in July in response to Trump’s rising military engagement in the region.
On Thursday, U.S. and Japanese troops began an 18-day live fire exercise on the northern Japanese island of Hokkaido, which was to include rocket artillery drills and involve 3,500 troops.
South Korean and U.S. troops are also gearing up for an annual joint drill from Aug. 21, called the Ulchi Freedom Guardian, where up to 30,000 U.S. troops will take part.
South Korean media on Friday called for Seoul to build nuclear weapons of its own to defend itself -- which would complicate the situation even further.
"Now is time to start reviewing nuclear armament," the Korea Herald said in an editorial.
After Pyongyang conducted two successful tests of an intercontinental ballistic missile last month, putting much of the mainland United States within reach, the paper warned: "Trust in the nuclear umbrella the US provides to the South can be shaken."
It urged Washington to deploy some of its atomic weapons to South Korea if it did not want to see a nuclear-armed Seoul.
But a South Korean bomb would infuriate Pyongyang, which says it needs nuclear weapons to defend itself against the threat of invasion, and make bringing it to the negotiating table even harder.
"The so-called 'balance of terror' would only turn the Korean peninsula into the hotbed of a nuclear arms race, not a peaceful peninsula," said Yang Moo-Jin, professor at the University of North Korea Studies in Seoul.
It could also trigger a "nuclear domino" in Asia, pushing others such as Tokyo and Taipei to seek their own arsenals, he added.
"Japan, in particular, would welcome it with open arms, because it provides a perfect excuse to revise its pacifist constitution and build its own nuclear weapons for 'self-defense'," he said.
The United States and South Korea remain technically still at war with North Korea after the 1950-53 Korean conflict ended with a truce, not a peace treaty.
Former defense officials and experts say any new military conflict with North Korea would likely escalate quickly to the use of nuclear weapons, bringing catastrophic casualties not seen since World War Two and an untold economic impact worldwide.
Guam, a tropical island more than 3,000 km (2,000 miles) to the southeast of North Korea, is home to about 163,000 people. It has a strategically located U.S. air base, a Navy installation that includes a submarine squadron and a Coast Guard group, and roughly 6,000 U.S. military personnel.