The threat of a nuclear catastrophe is at its highest level since the Cold War amid plummeting relations between Washington and Moscow and the ongoing posturing from North Korea and Iran, according to a former US Defence Secretary.

Increasing terror threats across the world and the erratic behaviour of US President Trump were touted as reasons for the heightened fears across the world by speakers at the International Luxembourg Forum on Preventing Nuclear Catastrophe in Paris.

William Perry, who served as the US Secretary of Defence for three years under President Clinton, said that the US and Russia have entered a “new Cold War”.

He said: “We are beginning a new Cold War, with the worst possible outcome a nuclear war between the US and Russia.

“Relations today between the US and Russia are comparable to the dark days of the Cold War. How could we have let that happen?”

Increasingly hostile relations between the US and Russia, North and South Korea and India and Pakistan have put the world on a knife-edge and with all of those countries possessing nuclear weapons, they could cause devastation at a moment’s notice.

Mr Perry added: “We could have the same number of casualties as all of World War Two, only these would happen in six hours instead of six years.”

Among the other speakers was former prime minister Tony Blair, who branded North Korea “abhorrent”.

He said: “We can threaten military action… But unless there are elements of which I am unaware in either the weakness of the North Korean defences or the strength of US capabilities, it is hard to think of a pre-emptive strike which would not result in catastrophic consequences.”

President Trump is expected to announce this week that he will scrap the landmark nuclear deal with Iran, which could increase global tensions even further.

Statesmen at the summit warned the decision not to certify the Iran agreement could make it more difficult to control North Korea’s nuclear ambition, given that Pyongyang are less likely to sign any disarmament agreement if they think Washington can ignore it in the future.

Mr Blair continued: “The sensible thing is to preserve the current agreement.”

He added that sticking to the agreement "means, for now at least, that Iran's nuclear program can be stalled”.

The news comes after Russia’s foreign secretary Sergey Lavrov told his US counterpart, Rex Tillerson, the escalation of tension on the Korean peninsula is “unacceptable”.

During a phone call with Secretary of State Mr Tillerson, Vladimir Putin's right hand man discussed Syria, Korea and Ukraine, the Russian foreign ministry revealed.

Mr Lavrov also told Mr Tillerson Moscow is demanding the US returns Russian diplomatic property seized in 2016 over suspected Russian interference in the general election.

The pair's phone call came just hours after Donald Trump's most senior general told the US Army to "stand ready" for war with North Korea.

General James 'Mad dog' Mattis warned it is impossible to tell what the future holds for the crisis, but urged US troops to be prepared for a confrontation with Kim Jong-un.

He said while Mr Trump is committed to finding a diplomatic solution, the US Army must "standby ready" to fight.

General Mattis said: "It is right now a diplomatically led, economic-sanction buttressed effort to try to turn North Korea off this path.

"Now what does the future hold? Neither you nor I can say, so there is one thing the US Army can do.

"And that is you have got to be ready to ensure that we have military options that our President can employ if needed.

Source: Daily Express