Britain should disown the US if it launched a "preventative" attack against North Korea to stop it developing nuclear weapons, according to a leading military think tank.

The unusually blunt advice from the Royal United Services Institute (RUSI), which is the intellectual powerhouse behind the UK's military establishment, comes amid growing concerns that such an attack is being seriously contemplated by Donald Trump's administration.

The US President threatened to totally destroy North Korea last week, and his senior advisers have given a series of interviews outlining the doctrine of "prevention".

Trump: US ready for N Korea 'military option'

A RUSI report says the UK "should refuse to rush into unconditional support for US action" if the US was to attack North Korea in an attempt to prevent it from further developing the ultimate weapon of mass destruction.

In the report, author Professor Malcolm Chalmers writes: "(The UK) should make it clear that it had not been asked for its views in advance and that it would not have supported military action even if it had been asked."


Privately, this view is widely shared within British military circles but ministers have been silent on the issue of a "preventative" attack on North Korea.

If one did go ahead, RUSI said, it would "involve a large-scale, US-led air and cyber offensive at an early stage, followed by massive North Korean retaliation against South Korea and US bases in the region using conventional, chemical and possibly nuclear weapons.

"In these circumstances, a full-scale invasion of North Korea (by the US and allies) would be highly likely."

As a result: "Casualties in such a conflict would likely reach the hundreds of thousands, even if no nuclear weapons were used. There could be far-reaching consequences for the global economy, involving sustained disruption of vital supply chains and markets."

Professor Chalmers insisted: "The UK Government should urge the US to reject proposals for preventive strikes."

July: North Korea launches intercontinental missile

Joseph Dunford, chairman of the US joint chiefs of staff, is one of several senior military and security figures who have been wheeled out to explain the doctrine of prevention.

He recently said: "We can't let a madman with nuclear weapons let on the loose like that.

"We have a lot of firepower, more than he has times 20, but we don't want to use it… I hope China solves the problem. But if China doesn't do it, we'll do it.

"I've told my counterparts, both friend and foe, it is not unimaginable to have military options to respond to North Korean nuclear capability.

"What's unimaginable to me is allowing a capability that would allow a nuclear weapon to land in Denver, Colorado. That's unimaginable to me. So my job will be to develop military options to make sure that doesn't happen."

China has signed up to strict economic sanctions against North Korea following Pyongyang's test of a ballistic missile which crossed Japan's northern Island of Hokkaido.

On Thursday, Beijing issued instructions to 120 Chinese companies to cease trading with North Korea and last week instructed its banks to do the same.

August: Japan's sirens ring out following N Korea missile

North Korea has dismissed Trump's threat to destroy it, saying it would "surely and definitely tame the mentally deranged US dotard with fire".

But a war, RUSI warned, would involve North Korea's "10,000 artillery pieces, as well as 500 to 600 short-range missiles, in hardened tunnels within range of South Korea" plus chemical and biological weapons.

Professor Chalmers added: "According to the South Korean government, North Korea has between 2,500 and 5,000 tons of chemical weapons, including anthrax, smallpox and, possibly, sarin nerve agent.

"During this first phase of the war, heavy casualties - both military and civilian - would be expected on both sides.

"Tens - and perhaps hundreds - of thousands would be killed by the end of the week.

"South Korea would become scenes of carnage."