US officials are concerned that a North Korean missile test launch will take place today.

Government sources in South Korea told the Yonhap News Agency that transporter erector launchers carrying ICBM launch tubes in North Pyongan province have been moved by North Korea.

Speaking anonymously, a US defense official said if a test was to go ahead it would be of either an intermediate-range missile or North Korea's ICBM - known as a KN-20 or a Hwasong-14, and would take place 'probably' today as North Korea celebrates Victory Day - the 64th anniversary of the signing of the Korean Armistice Agreement.

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Government sources in South Korea told the Yonhap News Agency that transporter erector launchers carrying ICBM launch tubes in North Pyongan province have been moved by North Korea

State-run news agency Korean Central News Agency (KCNA) reported that North Korea has threatened a 'merciless' nuclear strike 'at the heart of the US' if Kim Jong-Un's regime is threatened by America. Kim is pictured on July 4 after the test-launched of the Hwasong-14 ICBM

The threat was reported Tuesday in response to comments made by CIA Director Mike Pompeo (pictured) last week. He said Trump's administration needs to find a way to separate the country's Supreme Leader from their nuclear weapons

Experts assessed it could have put Alaska in range, bringing Pyongyang's long-held dream of a missile that can deliver an atomic warhead to the United States within reach.

A South Korean government source told Yonhap: 'Movements by transporter erector launchers carrying intercontinental ballistic missile (ICBM) launch tubes have been continuously observed in North Pyongan.

'There is a high possibility that the North may carry out (the test launch) around the July 27 armistice day.'

A second US defense official confirmed the fears, adding: 'They're setting up for something.'

If the launch goes ahead, it would be the second time Pyongyang has tested an ICBM after its July 4 rocket launch.

State-run news agency Korean Central News Agency (KCNA) reported a threat to strike the US on Tuesday in response to comments CIA Director Mike Pompeo made last week.

He said Trump's administration needs to find a way to separate the country's Supreme Leader from their nuclear weapons, CNN reported.

Pompeo said: 'As for the regime, I am hopeful we will find a way to separate that regime from this system.

'The North Korean people I'm sure are lovely people and would love to see him go.'

Though he did not say that the administration was actually working on that, KCNA said the comments are 'over the line'.

A new Defense Intelligence Agency (DIA) report says North Korea could produce nuclear intercontinental ballistic missiles (ICBMs) as soon as 2018 - not the 2020 previously expected North Korea's Hwasong-14 ICBM launch is pictured from July 4

'It has now become clear that the ultimate aim of the Trump Administration... is the regime change,' the agency added.

According to KCNA, a North Korean Foreign Ministry spokesperson said: 'The DPRK legally stipulates that if the supreme dignity of the DPRK is threatened, it must preemptively annihilate those countries and entities that are directly or indirectly involved in it, by mobilizing all kinds of strike means including the nuclear ones.

'Should the US dare to show even the slightest sign of attempt to remove our supreme leadership, we will strike a merciless blow at the heart of the US with our powerful nuclear hammer, honed and hardened over time.'

The report comes as US officials are saying North Korea could be capable of launching a nuclear attack on other continents within just one year.

North Korea's Hwasong-14 could theoretically reach the US - however to do so it would need a nuclear warhead that is too small to cause a serious threat, experts have said

Independent experts said today that the missile that was launched by Kim on July 4 isn't capable of carrying a nuclear payload across the Pacific - but that may not hold for long, officials told The Washington Post.

The Pentagon's Defense Intelligence Agency (DIA) says that North Korea is on track to build a nuclear-equipped intercontinental ballistic missile (ICBM) within the next year, shaving two years off the previous projections.

Both the DIA and the Office of the Director of National Intelligence (ODNI) declined to respond to the Washington Post about the classified assessments.

However, the ODNI's national intelligende manager for East Asia, Scott Bray, did say that the July 4 launch was 'one of the milestones that we have expected would help refine our timeline and judgments.'

'This test, and its impact on our assessments, highlight the threat that North Korea's nuclear and ballistic missile programs pose to the United States, to our allies in the region, and to the whole world,' he added.

'The intelligence community is closely monitoring the expanding threat from North Korea.'