It was another date which will live in infamy. But whereas President Franklin Roosevelt declared war in sombre tones to a joint session of Congress, Donald Trump did it his way.

The US president wore a white cap “USA” cap, dark jacket and white shirt open at the collar. He stood at a blue lectern bearing the US presidential seal and a black microphone, with the Stars and Stripes behind him, presumably at his Mar-a-Lago residence in Florida. He released a video on his own social media network, Truth Social, at 2.30am on Saturday – a time when most Americans are asleep but Trump is often found rage tweeting into the night.

In the space of eight minutes, Trump proceeded to upend half a century of US foreign policy, renege on his campaign promise to avoid the risk of forever wars and leave the Fifa boss, Gianni Infantino, with some explaining to do about why he gave Trump a made-up peace prize.

“There is also a beautiful medal for you that you can wear everywhere you want to go,” the oleaginous Infantino had told Trump last December. Trump was not wearing that medal on Saturday. Instead he delivered a performance that would have had soccer fans chanting: “Are you George Bush in disguise?”

Bush dragged the US into a tragic war in Iraq in 2003 that costs hundreds of thousands of lives and trillions of dollars and was recently crowned by the Council on Foreign Relations thinktank as the worst foreign policy decision in history. The avaricious Trump seems determined to seize that title for himself with another act of Middle Eastern regime change.

At least Bush tried to make a case to justify his invasion – mendacious as it was – and tried to convince the UN of its merits. Trump did not even bother. He amassed a huge “armada” in the Middle East with little explanation to Congress or the public. He did not mention Iran until more than an hour into this week’s State of the Union address.

Finally, when the bombs were already falling, he tried to offer a rationale in his social media video. The Iranian regime, he said, are “a vicious group of very hard, terrible people” whose menacing activities “directly endanger” the US and its allies. Trump ran through the history of the Iran hostage crisis, the Marine barracks bombing, the attack on the USS Cole and Iran’s hand in killing and maiming US troops in Iraq.

“It’s been mass terror, and we’re not going to put up with it any longer,” he said. But none of that answered a simple question: why now?

Trump went on to reference Iranian proxy groups “that have soaked the earth with blood and guts” and cite Hamas’s October 7 attacks on Israel. “Iran is the world’s number one state sponsor of terror and just recently killed tens of thousands of its own citizens on the street as they protested.”

Trump underlined the US policy that Iran can never have a nuclear weapon and glided past his own past claim that last June’s attack had “obliterated” its programme, contending that the US wanted to make a deal but Tehran refused. “They rejected every opportunity to renounce their nuclear ambitions, and we can’t take it anymore.”

The president said the US has undertaken “a massive and ongoing operation to prevent this very wicked, radical dictatorship from threatening America and our core national security interests,” – an ominous sign that Washington could be in for the long haul. The chairman-for-life of the new Board of Peace promised to “raze their missile industry to the ground” and “annihilate their navy”.

Then came an unexpected admission: “The lives of courageous American heroes may be lost, and we may have casualties. That often happens in war, but we’re doing this not for now. We’re doing this for the future, and it is a noble mission.”

Here was Trump, the reality TV president, understanding how desperate the optics will look if American servicemen and women return home in body bags, their lives sacrificed for a cause that the public little understand and still less believe in.

Ruben Gallego, a Democratic senator for Arizona and Iraq war veteran, responded on social media: “Draft dodger is willing to sacrifice working-class kids. How charitable of him.”

Trump warned members of the Islamic Revolutionary Guard to lay down their weapons. “You will be treated fairly with total immunity, or you will face certain death.”

But he saved the most extraordinary statement of all to the end. Having warned the Iranian people to stay sheltered because “bombs will be dropping everywhere”, Trump urged: “When we are finished, take over your government. It will be yours to take. This will be, probably, your only chance for generations.

“For many years, you have asked for America’s help, but you never got it. No president was willing to do what I am willing to do tonight. Now you have a president who is giving you what you want. So let’s see how you respond.”

There it was. After all those years of railing against neocons, foreign entanglements and regime change, Trump was calling for the overthrow of the Iranian government. The ghost of Donald Rumsfeld was smiling down on him; John Bolton and Lindsey Graham were high-fiving; Bush was dancing a jig of delight – this guy makes people miss me!

What happened? Nothing out of character. Trump the business was always a reckless gambler, whether building casinos in Atlantic City or launching his own ill-fated airline. Trump the politician has moved the US embassy to Jerusalem, killed Iranian commander Qassem Suleimani, imposed sweeping tariffs on trading partners and captured the Venezuelan president, Nicolás Maduro.

Each time, the experts warned of catastrophe; each time, something less than Armageddon happened, and so Trump felt increasingly emboldened to roll the dice again. (​Even his demolition of the White House East Wing was a case of act now, let others ask questions later.) Iran, however, is a gamble of an entirely different magnitude and the president is yet to articulate a long-term strategy beyond hoping for the best. The lesson of Iraq is that regime change is the easy part, but what happens next can be hell.

Yet still the man who was given a Nobel peace prize by true winner María Corina Machado – and kept it! – has launched Operation Epic Fury on an unready world. As Ben Rhodes, a former deputy national security adviser under President Barack Obama, tweeted: “Trump’s second term has been the worst-case scenario.”