The US Defense Secretary James Mattis issued a dramatic ultimatum to North Korea on Wednesday and said that it should “not invite destruction of your people.”

This comes after the North Korea said it was "carefully examining" plans for a missile strike on the US Pacific territory of Guam.

Earlier, US President Donald Trump told the North that any threat to the United States would be met with "fire and fury".

North Korea has made no secret of its plans to develop a nuclear-tipped missile able to strike the United States and has ignored international calls to halt its nuclear and missile programs.

North Korea should "cease any consideration of actions that would lead to the end of its regime and destruction of its people" Mattis said.

"North Korea must choose to stop isolating itself and stand down its pursuit of nuclear weapons," Mattis said in a written statement, adding that the "regime's actions will continue to be grossly overmatched by ours and would lose any arms race or conflict it initiates."

Mattis has consistently said that he prefers to resolve issues over North Korea's missile and nuclear programs through diplomacy, noting military action could yield catastrophic consequences.

On Wednesday, Mattis called on North Korean leader Kim Jong Un to cooperate with the international community.

"Kim Jong Un should take heed of the United Nations 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 said.

In the meantime, US Secretary of State Rex Tillerson sought to assure Americans there was no imminent threat.

The US has large military bases in the Guam, strategic bombers and about 163,000 people.