The Pentagon says a group of US warships is headed to the western Pacific Ocean to provide a physical presence near the Korean Peninsula.

The strike group, called Carl Vinson, includes an aircraft carrier and will make its way from Singapore towards the Korean Peninsula.

The development comes in response to North Korea's "reckless, irresponsible" conduct, a US navy official said, referring to recent missile tests.

"US Pacific Command ordered the Carl Vinson Strike Group north as a prudent measure to maintain readiness and presence in the Western Pacific," Commander Dave Benham, spokesperson at US Pacific Command, told AFP news agency.

 
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"The number one threat in the region continues to be North Korea, due to its reckless, irresponsible and destabilising programme of missile tests and pursuit of a nuclear weapons capability."

In a statement late on Saturday, the US navy's Third Fleet said the strike group had been directed to sail north, but it did not specify the destination.

The military vessels will operate in the western Pacific rather than making previously planned port visits to Australia, it said.

Deployed from San Diego to the western Pacific since January 5, the Carl Vinson strike group has participated in numerous exercises with the Japan Maritime Self Defence Force and Republic of Korea Navy, various maritime security initiatives, and routine patrol operations in the South China Sea.

The US decision comes close on the heels of a US missile strike on Syria that was widely interpreted as putting North Korea on notice over its refusal to abandon its nuclear ambitions.

Missile quest

Earlier this month, North Korea tested a liquid-fuelled Scud missile which only travelled a fraction of its range.

This year North Korean officials, including leader Kim Jong-un, have repeatedly indicated that an intercontinental ballistic missile test or something similar could be coming, possibly as soon as April 15, the 105th birthday of North Korea's founding president and celebrated annually as the Day of the Sun.

North Korea is on a quest to develop a long-range missile capable of hitting the US mainland with a nuclear warhead, and has so far staged five nuclear tests, two of them last year.

 

Expert satellite imagery analysis suggests it could well be preparing for a sixth, with US intelligence officials warning that North Korea could be less than two years away from developing a nuclear warhead that could reach the continental US.

Earlier this week, US President Donald Trump and Chinese President Xi Jinping met in Florida, where Trump urged his counterpart to do more to curb North Korea's nuclear programme.

Trump's national security aides have completed a review of US options to try to curb North Korea's nuclear and missile programmes.

These include economic and military measures but lean more towards sanctions and increased pressure on China to restrain North Korea.

In February the North simultaneously fired four ballistic missiles off its east coast, three of which fell provocatively close to Japan, in what it said was a drill for an attack on US bases in the neighbouring Asian country.

Last August North Korea also successfully test-fired a submarine-launched ballistic missile 500km towards Japan, far exceeding any previous sub-launched tests, in what Kim described as the "greatest success".

north korea ballistic missile test nuclear infographic