North Korea: 'US has now gone seriously mad'

North Korea reiterated its vow to launch "full-out war" with nuclear weapons on Saturday as an American naval strike carrier was set to arrive off the tense Korean peninsula in a matter of days.

Tensions between the United States and the North have soared in recent weeks as a series of North Korean missile tests have wrought ever-more bellicose warnings from President Donald Trump's administration about curtailing its nuclear weapons programme.

The US supercarrier Carl Vinson will arrive in the Sea of Japan in days, American Vice President Mike Pence said on Saturday, after days of mixed messages from Washington over the warship's whereabouts.

The strike group was supposedly steaming towards North Korea last week amid concerns the North is ramping up for a sixth nuclear test, with Pyongyang threatening to hit back at any provocation.

But the US Navy - which had earlier said the aircraft carrier would sail north from waters off Singapore as a "prudent measure" to deter North Korea, admitted on Tuesday the ships were in fact sent away from Singapore and towards Australia to conduct drills with the Australian navy.

UN calls for calm over US-North Korea tensions The aircraft carrier will arrive "in a matter of days", said Pence after the location of the naval strike group became contentious.

US officials have repeatedly warned "all options are on the table" - including military strikes - to curb the North's nuclear ambitions.

North Korea remained defiant in the face of the American show of force.

"Now that we possess mighty nuclear power to protect ourselves from US nuclear threat, we will respond without the slightest hesitation to full-out war with full-out war and to nuclear war with our style of nuclear strike, and we will emerge victor in the final battle with the United States," the North's foreign ministry said in a statement.

The North will celebrate the 85th anniversary of the foundation of its Korean People's Army on Tuesday and has marked important events in the past by launching missiles or conducting nuclear tests.

Tuesday's anniversary also comes as the North finishes winter military drills and as South Korea and the United States wrap up annual joint military exercises.

The official Rodong Sinmun newspaper said on Saturday in a commentary that North Korea wouldn't hesitate to launch a pre-emptive strike if provoked.

Pence warns North Korea 'era of strategic patience is over'

"The US has now gone seriously mad. It is mulling frightening the DPRK and achieving something with nuclear strategic bombers, nuclear carriers, etc. However, the army and people of the DPRK will never be browbeaten by such bluffing," it said, referring to the North by its official name, the Democratic Republic of Korea.

"Under the situation where the US hurts the DPRK by force of arms, we have nothing to be bound to. The DPRK will answer to such war moves and provocations with pre-emptive strike of its own style and a great war of justice for national reunification."

Pence also renewed US calls for Beijing to use its "unique" position to bring Pyongyang to heel.

"The steps we're seeing China take, in many ways unprecedented steps, bringing economic pressure to bear on North Korea are very welcome," Pence said. "We do believe China can do more."

Tensions between Pyongyang and Washington go back to the 1950-53 Korean War, which ended in an armistice, not a peace treaty. But the heat has been rising rapidly since Trump took office in January.