The Trump administration was scrambling on Sunday to justify its claim that the killing of Iran’s most powerful general was about stopping a war rather than starting one, as tensions spiralled by the hour.

Amid growing scepticism over the intelligence behind the lethal strike against Qassem Suleimani, the US president and Iranian officials hurled increasingly dire warnings at each other. Opponents cautioned that if Donald Trump carries out a tweeted threat to attack dozens of Iranian sites including non-military cultural targets, he would be guilty of a war crime.

The president went to his golf course in Florida and left secretary of state Mike Pompeo to defend the assertion that the drone strike against Suleimani in Baghdad prevented an imminent attack on US interests.

“We would have been culpably negligent had we not taken this action,” Pompeo said on NBC’s Meet the Press. “The American people would have said that we weren’t doing the right thing to protect and defend American lives. President Trump has been crystal clear.”

Profile Who was Qassem Suleimani? Show Qassem Suleimani, killed by a US drone strike in Baghdad, had become well known among Iranians and was sometimes discussed as a future president. Many considered Suleimani to have been the second most powerful person in Iran, behind supreme leader of Iran Ali Khamenei, but arguably ahead of President Hassan Rouhani. He was commander of the Quds Force, the elite, external wing of the Iran’s Islamic Revolutionary Guard Corps, which the Trump administration designated as a terror organisation in April last year. He was born in Rabor, a city in eastern Iran, and forced to travel to a neighbouring city at age 13 and work to pay his father’s debts to the government of the Shah. By the time the monarch fell in 1979, Suleimani was committed to the clerical rule of Ayatollah Ruhollah Khomeini, and joined the Revolutionary Guards, the paramilitary force established to prevent a coup against the newly declared Islamic Republic. Within two years, he was sent to the front to fight in the war against the invading Iraqi army. He quickly distinguished himself, especially for daring reconnaissance missions behind Iraqi lines, and the war also gave him his first contact with foreign militias of the kind he would wield to devastating effect in the decades to come. By the the time the Iraq government fell in 2003, Suleimani was the head of the Quds force and blamed for sponsoring the Shia militias who killed thousands of civilian Iraqis and coalition troops. As fighting raged on Iraq’s streets, Suleimani fought a shadow war with the US for leverage over the new Iraqi leadership. Once described by American commander David Petraeus as ‘a truly evil figure’, Suleimani was instrumental in crushing street protests in Iran in 2009. In recent months outbreaks of popular dissent in Lebanon, Iraq and Iran were again putting pressure on the crescent of influence he had spent the past two decades building. Violent crackdowns on the protests in Baghdad were blamed on militias under his influence.

Eighteen months before his death, Suleimani had issued Donald Trump a public warning, wagging his finger and dressed in olive fatigues. “You will start the war but we will end it.” Michael Safi Photograph: Mehdi Ghasemi/AFP

The secretary went on the claim that “there were in fact plots that [Suleimani] was working on that were aimed directly at significant harm to American interests throughout the region, not just in Iraq”.

But he was unable to provide specifics.

When host Chuck Todd asked if retaliation against US citizens should now be expected, Pompeo admitted: “It may be that there’s a little noise here in the interim.”

It was a remark that could come to be seen as flippant if American lives are lost.

Suleimani, Iran’s top military commander held responsible for thousands of deaths, was killed on Friday in a drone strike at Baghdad airport, a stunning attack analysts said brought the US and Iran closer to war than at any point in the past 40 years.

Critics fear Trump has opened Pandora’s box. On Sunday the Iraqi parliament passed a resolution calling on the government to expel US troops. Around 5,000 remain in Iraq, most in an advisory capacity.

Wendy Sherman, a former under secretary of state for political affairs, tweeted: “The Iraqi parliament vote to expel US troops is a major win for Iran. Just one piece of fallout against our interests by [Donald Trump’s] decisions.”

Iran also announced it would no longer meet its commitments under the international nuclear deal Trump left in 2018.

US media reports have suggested that the evidence Suleimani was plotting an attack was circumstantial at best and that a strike was among several options presented to Trump that few expected him to take. Pompeo, however, insisted the action – taken without congressional authorisation – was both lawful and necessary.

On ABC’s This Week, he said there had been “no scepticism” among senior leaders.

“The intelligence assessment made clear that no action – allowing Suleimani to continue his plotting, his planning, his terror campaign – created more risks than taking the action that we took last week. We reduced risks.”

Pompeo was pressed on CNN’s State of the Union about how “imminent” the attacks were.

“If you’re an American in the region, days and weeks – this is not something that’s relevant,” he said. “We have to prepare, we have to be ready, and we took a bad guy off the battlefield.”

Democrats seized on the lack of details. Pete Buttigieg, a military veteran and candidate for president, told CNN: “The secretary of state just now, when asked whether this strike prevented directly an attack, he did not prove, he did not demonstrate, he did not even claim that the answer was yes.”

Buttigieg added: “Now, let’s be clear – Qassem Suleimani was a bad figure. He has American blood on his hands. None of us should shed a tear for his death. But just because he deserved it doesn’t mean it was the right strategic move. This is about consequences.”

The jarring intervention by Trump – who is facing an impeachment trial and tough re-election campaign – seemed to fly in the face of his “America first” policy and pledge to pull troops out of the Middle East.

After Tehran promised retaliation, Trump threatened to hit 52 sites – “some at a very high level & important to Iran & the Iranian culture” – if Iran attacked Americans or US assets. Such an action would almost certainly result in civilian deaths.

On Sunday, he followed up with a tweet he claimed was sufficient to notify Congress “that should Iran strike any US person or target, the United States will quickly & fully strike back, & perhaps in a disproportionate manner.”

The word “disproportionate” was sure to raise alarm.

Hossein Dehghan, military adviser to Iran’s supreme leader, told CNN that if Trump went ahead with an attack, “he should accept that he is a war criminal and must be tried in a relevant court”.

Dehghan warned that Iran’s response to the airstrike “for sure will be military and against military sites”, adding: “The only thing that can end this period of war is for the Americans to receive a blow that is equal to the blow they have inflicted. Afterward they should not seek a new cycle.”

Iranian information minister Mohammad Javad Azari-Jahromi tweeted: “Like Isis, Like Hitler, Like Genghis! They all hate cultures. Trump is a terrorist in a suit. He will learn history very soon that NOBODY can defeat ‘the Great Iranian Nation & Culture’.”

Targeting cultural sites is a war crime under a 1954 Hague convention. In 2017, the United Nations security council passed unanimously a resolution condemning the destruction of heritage sites.

Chris Murphy of Connecticut, a Democrat on the Senate foreign relations committee, tweeted: “Targeting civilians and cultural sites is what terrorists do. It’s a war crime. Trump is stumbling into a war of choice. A war entirely of his making. A war that will get thousands of Americans killed. Congress must stop him.”﻿