The US president is marching the world towards nuclear war. It’s time we started taking this seriously.

“[F]ire, fury, and, frankly, power, the likes of which the world has never seen.” That is what Donald Trump promised if North Korea made “any more threats to the United States”.

Two days later he doubled down, saying the first statement “maybe wasn’t tough enough”. By the next morning, he was tweeting, “Military solutions are now fully in place, locked and loaded, should North Korea act unwisely”.

These words aren’t ambiguous. They aren’t open to interpretation. The president of the United States is threatening to start a war on the Korean peninsula that would almost certainly be the bloodiest global conflict since World War Two.

There is every chance that such a conflict would go nuclear, either because the US used nuclear weapons in a first strike, or because the North Korean military responded to a serious (even non-nuclear) assault as it has promised and trained to do – with nuclear, chemical and biological weapons strikes on US forces in Japan and South Korea. This would almost certainly result in a US nuclear counter-strike.

The consequences of such a conflict would be devastating. Seventy-five million people live on the tiny Korean peninsula. Thirty-eight million more live in Tokyo, well within range of North Korean missiles. That is more than four times the population of Australia in the direct firing line. And such a war on its doorstep could easily grow to involve China, as happened in the first Korean war.

There is a widespread tendency to downplay the threat, to think such a war is too unthinkable to happen.

Trump, it is assumed, is all bluster. Given the stakes, that is a big bet. It’s not like the idea of using a foreign war to overcome domestic unpopularity is new to him. In a 2012 tweet, which has been widely retweeted in recent weeks, Trump said: “Polls are starting to look really bad for Obama. Looks like he’ll have to start a war or major conflict to win. Don’t put it past him!”

US Republican senator Lindsey Graham said on NBC that Trump told him that claims there is not really a military option in North Korea are “just false”.

“There is a military option to destroy North Korea’s nuclear program and North Korea itself”, Graham said. Trump said he was not going to allow “this madman” Kim Jong-un “to have a missile that could hit America”.

“If there’s going to be a war to stop him, it will be over there”, Graham said. “If thousands die, they’re going to die over there. They’re not going to die over here – and [Trump’s] told me that to my face.”

The other argument that war is unlikely is that whatever Trump wants, the Pentagon brass and his top officials, such as chief of staff John Kelly and secretary of defence James Mattis, would never let him start a war on a whim.

That is possible. Significant sections of the US military and political establishment recognise that the consequences of a new Korean war could be diabolical for the US, and are at best extremely unpredictable.

But Trump’s powers to wage war do not face the checks and balances that his domestic agenda is subject to. He is the commander in chief of the armed forces: if he gives an order, it must be obeyed.

The kind of military build-up that would be necessary to overthrow the North Korean regime, and also have a slim chance of preventing a North Korean nuclear strike on South Korea or Japan would, it is true, take months, giving some time for opposition to build. On the other hand, the US president has the power to order an immediate nuclear strike, or a series of strikes, that would result in missiles being launched just minutes later.

Moreover, the madness of Trump is not just a product of his own demented narcissism, or of the revolt of a new right wing populism. Like so many mad kings before him, Trump is the product of an empire in crisis. His “make America great again” slogan had an appeal not only because it reflected bitterness at declining living standards for sections of white workers and the middle class, but also because it articulated the fact that US imperialism is no longer all powerful.

For the US ruling class – which emerged from the Second World War ascendant over all the old European empires, and which 40 years later vanquished its only military rival, the USSR – the realisation that the 21st century is not going to be a new American century is deeply traumatising.

North Korea is a symbol of declining US power. The US has cajoled and bullied and menaced the country for decades: encircling it with US troops, ships and, at times, nuclear weapons; openly threatening to overthrow its government; and imposing sanctions that have starved its people and nearly precipitated economic collapse. But it has not been able to stop the North Korean nuclear program, which now has or is very close to having nuclear weapons capable of striking US cities.

The US ruling class has no one but itself to blame for this situation. The determination of the North Korean regime to develop nuclear weapons is a direct response to the US invasion of Iraq, which overthrew and eventually killed Saddam Hussein precisely because he did not have such weapons.

As professor John Delury, of the Yonsei University Graduate School of International Studies in Seoul, told the BBC last year: “Above all else, North Korea’s nuclear program is about security – it is, by their estimation, the only reliable guarantee of the country’s basic sovereignty, of the Communist regime’s control, and of the rule of Kim Jong-un.

“North Korea learned from Iraq that Saddam Hussein’s mistake was he did not possess the weapons of mass destruction he was falsely accused of having. Libya taught a similar lesson.”

The US is desperate to avoid North Korea proving its doctrine that the only way to guarantee regime survival is to establish a nuclear force capable of inflicting mass destruction on US cities, or at least those of US allies.

But there is now no way to prevent this other than through a war that could kill millions of people. Such a war should be unthinkable, but if the bloody history of the US rise to global supremacy tells us one thing, it is that there are few lengths to which its ruling class will not go to establish and defend its power.

Even if war is not the most likely short term outcome of this latest round of sabre rattling, the fact that it is a real possibility should be creating a torrent of outrage around the world.

But it is not. Our own government has gone out of its way to tie itself to the Trump death-train. Malcolm Turnbull called a press conference last week to proclaim fealty to the US alliance, declare Australia’s support for the US in a war with North Korea and insist that we should “be under no misapprehension, in terms of defence, we are joined at the hip”.

Turnbull’s willingness to sell his soul to the right wing of his party is sickening enough in the case of marriage equality. When he does it to commit Australia to back Trump in a potential nuclear war in Asia, it is beyond criminal.

Bill Shorten is no better. Labor has spent the last few weeks trying to channel its inner Corbyn, which is hard, because it doesn’t exist. But however good a job Shorten was doing on same sex marriage or “inequality”, he fell into line with all the grace of the over-enthusiastic lemming when it came to North Korea.

“Australians should be reassured that on this matter of North Korea and our national security, the politics of Labor and Liberal are working absolutely together”, Shorten said.

Let’s make it clear what we are talking about. Everyone in Australian politics, aside from Tony Abbott and the right wing of the Liberal and National parties, agrees that a deranged lunatic has his finger on the US nuclear codes. But most mainstream politicians, Bill Shorten as much as Malcolm Turnbull, think we have to maintain the alliance with the US, and that means going along with whatever comes out of Trump’s mouth. Shorten has more space to be critical of Trump because he is not in government. But his position is basically identical to Turnbull’s – the US alliance must not be criticised.

The Greens, to their credit, have strongly criticised the government’s stance, and reiterated their call to break the US alliance. But the escalation of the Korea crisis demands more than words. It is time to start organising an anti-war movement in Australia that can stand up and fight the politicians who contemplate unleashing the hell of nuclear war.