He writes in a piece for the Guardian:

.. at a time when his unprecedented sanctions had stirred unrest inside Iran, the political elite has just been handed a rallying cry. The strike on Suleimani, whose status approached that of national icon, will harden popular sentiment against the US while simultaneously shoring up the regime.

For all his crowing about the decisive blow dealt to an insolent enemy, Trump may be about to discover that the problem with martyrs is that they live forever.

Tom Tugendhat told BBC News: “Well I’ve long believed that the purpose of having allies is that we can surprise our enemies and not each other, and it’s been a pattern, sadly, which has been a bit of a shame, that the US administration of late has not shared with us and that is a matter of concern.

“I would urge the US administration to share much more closely with allies, particularly those who are fighting alongside in the region, including us.”

He added: “But this is a tactical point. A strategic point is that the United States has rocked the regime much more than for example the death of Osama bin Laden rocked the jihadist movement. This is a much more significant incident.”

Tugendhat said the airstrike “will doubtless have consequences”.

Speaking on CNN, Pompeo said the Iranian general was “actively plotting in the region to take action, big actions he described it, that would have put thousands, if not hundreds American lives at risk”.

Pompeo said the airstrike was driven by “an intelligence-based assessment”, adding: “The American people also know the history of Qassem Suleimani. Hundreds of American lives on his hands too.”

He added: “Last night was the time we needed to strike to make sure that this imminent attack that he was working actively was disrupted.”

When asked if there was any imminent threat to US homeland, Pompeo said: “These were threats located in the region.”

Pompeo went on to say that Donald Trump has shown “enormous restraint to date”, but added the government had to act because “the risk of doing nothing was enormous. Intelligence community made that assessment.”

You can watch the full interview below.

The Lib Dem acting leader, Ed Davey, said: “Iran is governed by a brutal regime which has been openly hostile to the west.

“Donald Trump has yet again radically and recklessly escalated tensions in an area where peacekeeping was already on a knife edge.

“There is a real danger this will stoke further conflict, undermining peace and stability in the region. Given the severity of the crisis, the prime minister must make a statement about the UK’s position immediately.

“The UK should not automatically follow whatever position the Trump administration takes, but work with a broader group of concerned states at the United Nations.”

There is also concern that the Iraqi parliament will seek to expel the 5,000 US troops from Iraq with unpredictable consequences for the region, including the fight against Islamic State.

These private concerns were voiced amid public European calls for all sides to de-escalate the crisis, appeals that are unlikely to be heeded in Tehran, which is intent on some form of reprisal.

In a statement that neither condemned nor condoned the killing of Suleimani, the UK foreign secretary, Dominic Raab, said: “We have always recognised the aggressive threat posed by the Iranian Quds force led by Qassem Suleimani. Following his death, we urge all parties to de-escalate. Further conflict is in none of our interests.”

France’s European minister, Amélie de Montchalin, also called for calm. Speaking on French radio, she said any military escalation was always dangerous. “At European level, we have to work in collective multilateral frameworks and prevent the powers, one against the other, from playing their game in an unpredictable manner,” she said. “Our role is not to stand on one side or the other, it is to speak with everyone.”

She said the French president, Emmanuel Macron, would be consulting widely on Friday

The US secretary of state says he has spoken to the British foreign secretary, Dominic Raab, China’s top diplomat, Yang Jiechi, and Germany’s minister of foreign affairs, Heiko Maas, about the US decision to kill Suleimani, who commanded Iran’s elite Quds force.

The Iraqi military said it was a clear breach of the US mandate in Iraq, according to a report by Reuters.

“The Joint Operations Command mourns the hero martyr ... who was martyred last night in a cowardly and treacherous attack carried out by American aircraft near Baghdad international airport,” it said in a statement.

“We affirm that what happened is a flagrant violation of Iraqi sovereignty and a clear breach by the American forces of their mandate which is exclusively to fight Islamic State and provide advice and assistance to Iraqi security forces.”

In a statement, Netanyahu said: “Just as Israel has the right of self-defence, the United States has exactly the same right.

Ian Bond, foreign policy director at the Centre for European Reform, tweeted that the airstrike was a “big escalation” by Trump.

But he said that Iran was not likely to want to provoke a war with the US. “The significance of this strike is that it is a declared assassination of a senior officer in another state with whom the US is not in a declared armed conflict and conducted on the territory of a third party,” he said.

“That’s a very significant development in and of itself. Ultimately Iran does not want to provoke a full-scale conflict. I would expect there will be attacks on US forces, but they will be conducted with care.”

Watling added if the UK was seen by Iran to be participating in US actions it could lead to the capture or arrest of British citizens in the region. “The Iranians do not draw a direct line between the UK and US. However, if the UK is perceived to be participating in US actions then they will directly target UK interests,” he said.

He added: “The UK is not automatically the first target. Citizens in Iraq, Syria and Lebanon would certainly potentially be at risk. Dual nationalities in Iran will certainly be at risk of arrest under espionage charges.”

The former US national security adviser tweeted his congratulations to all involved in assassinating Iran’s top general, describing the strike as long in the making.

In a Twitter thread, Agnès Callamard said the US would need to prove the individual targeted constituted an imminent threat to others. “An individual’s past involvement in ‘terrorist’ attacks is not sufficient to make his targeting for killing lawful,” she said.

On the White House statement about the airstrike, Callamard said: “The statement fails to mention the other individuals killed alongside Suleimani. Collateral? Probably. Unlawful. Absolutely.”

In a statement, Corbyn notes: “The UK government should urge restraint on the part of both Iran and the US, and stand up to the belligerent actions and rhetoric coming from the United States.”

Nick Robinson, BBC’s Radio 4’s Today programme host, described the event as “a very early test for those who want to be leader of the opposition”.

Keir Starmer, the current frontrunner to win the Labour leadership, tweeted that the incident is “an extremely serious situation” and called for all sides to de-escalate tensions.

Jess Phillips, the Labour MP who is expected to formally declare her bid to lead the Labour party, said: “Reckless foreign policy does not show strength. It’s not a game. The consequences of the escalating tensions between the US and Iran are not to be underestimated, not just once again on the civilians in the region but on the whole world.”

Robinson asked Melanie Onn, former Labour MP who recently lost her seat but is supporting Phillips: “Should people like Jess Phillips take a sort of Corbyn stand, or should she be wary of those who criticise Mr Corbyn for seeming to back the wrong side in international conflict.” In response, Onn said: “I don’t think that anyone who is trying to emulate somebody else is the right person for the Labour party.”

Oil prices rose over $2 a barrel, while gold and other safe-haven assets jumped on Friday, Reuters reported, adding “traders were clearly spooked” by Qassem Suleimani’s death.

The news agency also reported that foreign oil companies were evacuating dozens of employees with US citizenship from Basra in Iraq, citing company sources.

In a written statement, Raab said: “We have always recognised the aggressive threat posed by the Iranian Quds force led by Qassem Suleimani. Following his death, we urge all parties to de-escalate.

“Further conflict is in none of our interests.”