US officials and South Korea's president in recent days have played down the risk of an imminent conflict after Washington and Pyongyang exchanged fiery rhetoric last week.
The defense chief said the Pentagon is able to tell "within moments" where North Korea's missiles are headed, and said the United States would try to shoot down anything that threatened America.
Mattis told reporters that the US military would know the trajectory of a missile fired by North Korea within moments and would "take it out" if it looked like it would hit the US Pacific territory.
China is North Korea's main economic partner and political backer, although relations between Beijing and Pyongyang have deteriorated amid the North's continuing defiance of China's calls for restraint.
Japan conducted air maneuvers with U.S. bombers southwest of the Korean peninsula on Wednesday involving two U.S. Air Force B-1B Lancer bombers flying from Andersen Air Force Base on Guam and two Japanese F-15 jet fighters, Japan's Air Self Defence Force said in a news release.
"I am certain the United States will respond to the current situation calmly and responsibly in a stance that is equal to ours", he said. Other nuclear-armed regimes have similarly engaged in "unspeakable brutality" against their own people and posed direct threats to the USA, but they have refrained from using nuclear weapons against the US and its allies because they believed that they would invite their own destruction if they did so.
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"The Dodge Challenger fled the scene, but was located and stopped a short time later by Charlottesville Police". Fields is due back in court on August 25.
The president added, "They will be met with fire, fury and frankly power the likes of which this world has never seen before".
But Foreign Minister Sigmar Gabriel and other officials said it was premature to consider talks.
China has repeatedly called for all sides to exercise restraint and remain calm, and while it has signed up for tough United Nations sanctions on North Korea, it says the key to a resolution lies in Washington and Pyongyang talking to each other, rather than expecting China to do all the work. "He encouraged strengthening trilateral cooperation between the U.S., (South Korea) and Japan", U.S. military spokesman Captain Darryn James said.
Pompeo said that USA intelligence has a "pretty good idea" about North Korea's near-term intentions after monitoring recent intercontinental missile tests and the country's improved ability to manufacture nuclear weapons.
North Korea threatened to shoot four missiles into the sea off Guam following heated exchanges with the US over Pyongyang's nuclear weapons program.
"Any second Korean War would have no choice but to spread into a nuclear war", it said in a commentary.
If he orders them to fly, North Korea has its excuse to launch. "Regardless of whatever twist and turns we could experience, the North Korean nuclear program should absolutely be solved peacefully, and the (South Korean) government and the USA government don't have a different position on this".