Defence Secretary Jim Mattis on Wednesday warned North Korea to "stand down" from pursuing nuclear weapons and cease considering actions that would lead to the "end of its regime", after Pyongyang threatened missile strikes against US strategic military installations in Guam.
The strong statement from Mattis came a day after US President Donald Trump said North Korea's threats against the US will be met with "fire and fury".
"The DPRK must choose to stop isolating itself and stand down its pursuit of nuclear weapons. The DPRK should cease any consideration of actions that would lead to the end of its regime and the destruction of its people," Mattis said.
DPRK stands for Democratic People's Republic of Korea, the official name of North Korea.
Mattis said the US and its allies have the capabilities and commitment to defend themselves.
"Kim Jong-Un should take heed of the United Nation Security Council's unified voice, and statements from governments the world over, who agree the DPRK poses a threat to global security and stability," he asserted.
While the State Department is making every effort to resolve this global threat through diplomatic means, it must be noted that the combined allied militaries now possess the most precise, rehearsed and robust defensive and offensive capabilities on Earth, Mattis said.
"The DPRK regime's actions will continue to be grossly overmatched by ours and would lose any arms race or conflict it initiates," said the US defence secretary.
A day earlier Trump warned the North against threatening the US. "North Korea best not make any more threats to the US. They will be met with fire and fury like the world has never seen," he told reporters at his vacation home in New Jersey.
He was responding to reporters' questions on the North Korean nuclear capabilities. "As said, they will be met with fire, fury, and, frankly, power the likes of which this world has never seen before," he said.
Trump's remarks came amid reports that North Korea was nearing to obtain an atomic weapon that can strike the US. Media reports said the North has successfully miniaturised a nuclear warhead that can fit inside its missiles.
North Korea responded by warning to attack Guam.
Democratic leaders criticised Trump for his statement on North Korea.
"President Trump's threat against North Korea is reckless and shows a serious lack of judgment. No matter how much the Kim regime deserves international condemnation and action - which it does - it is not a strategic or responsible response to issue wild threats of destruction," said House Democratic Whip Steny H Hoyer.
Congressman Dan Kildee of Michigan was in South Korea wehn the North Korean regime tested another missile.
"There's obviously growing concern, and that concern is fueled when the president of the US deliberately uses language that escalates sort of the war of words and I think, unfortunately, matches the tone and tenor of North Korean officials," Kildee said.
"We ought not engage in this sort of belligerent talk," he told CNN.