The United States National Security Advisor (NSA) Lieutenant General HR McMaster has said a nuclear-armed North Korea poses a real danger to the world, including its allies China and Russia.

McMaster was quoted by Fox News as saying that if Pyongyang acquires nuclear weapons then it would be "the most destabilising development" in the post-World War II period.

"It is something that places us at direct risk, but places the world at risk. This is a regime that's never met a weapon that it hasn't proliferated. It's a regime who's said clearly its intentions are to use that weapon for nuclear blackmail and then to quote, 'reunify' the peninsula under the red banner," McMaster said.

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HR McMaster

"So he would use this to get — extract payoffs, as the regime has done with their nuclear program in the past, and to drive the States and our allies away from this peninsula that he would then try to dominate. And if you want to know what life looks like under a North Korea regime, you just have to look north of the 38th parallel," he added.

The NSA also said there are other serious concerns to be considered and one of them is North Korea would proliferate its nuclear weapons or attempt to sell those to other countries.

"And there's never been a weapons system that North Korea has developed that it hasn't sold to somebody else," he said.

McMaster said there is a real danger to Russia, China and to all the other nations if the Kim Jong-Un-ruled nation acquires nuclear weapons.

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North Korean leader Kim Jong Un provides guidance on a nuclear weapons program in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang September 3, 2017. [Representational Image]Reuters

"You have that direct threat, but you also have the threat the potential of Japan, South Korea, others, arming themselves, possibly even with nuclear weapons. That is not in China's interest; it's not in Russia's interest," he said.

Tensions between the US and North Korea have escalated as the leaders of the two countries have been locked in a bitter war of words over Pyongyang's ambitious nuclear programme.

The situation worsened when US President Donald Trump, during his first address to the United Nations General Assembly (UNGA), vowed to annihilate North Korea if it posed any threat to the US and its allies

Pyongyang, on various occasions, has vowed to attack the United States if it feels threatened. The latest missile tests conducted by the country were capable of reaching the US Pacific territory of Guam.