The question is not if Iran will retaliate, it's how and when that will take place

The British government has little influence on what Washington will do next, and none on what Iran will do in retribution for the killing of Qassem Soleimani

“You may not be interested in war, but war is interested in you,” warned Leon Trotsky. That is the position America’s allies and adversaries find themselves in after the killing of Qassem Soleimani.

The Trump administration did not inform any of its close partner states that it was about to kill the Iranian commander in a missile strike.

Boris Johnson was seemingly oblivious to what was going to happen as he enjoyed his Caribbean holiday, the “special relationship” between the US and the UK, and his own supposedly personal one with Donald Trump, apparently counting for nothing. As a result there was no immediate upgrading of security for British forces in the region, which work closely with the Americans in some places, nor for other British citizens in the region.

The Foreign Office issued its standard travel advice a day later, cautioning people about going to Iraq and Iran. The UK’s official response to the most combustible escalation in the Middle East in recent years came not from the prime minister, who remains on Mustique, but from Dominic Raab.

The foreign secretary urged all parties to remain calm, saying that “further conflict is in none of our interests”. In reality, however, what happens now is outside London’s control. It has little influence on what Washington will do next, and none on what Iran will do in retribution for the killing.

The question now is how and when that retaliation will take place and just how many other countries will be drawn into what happens then. Those countries that side openly with the US in the confrontation could be seen as legitimate targets.

There are varying dimensions to this. There is nothing to suggest that Britain approved the killing of Soleimani. Indeed this country, along with France, Germany, Russia and China has stood by the agreement between Iran and international powers over Tehran’s nuclear programme as Trump tries to sabotage it.

But there is the burden of history. As I have found while reporting from Iran, there is a dark legacy from Britain’s past in suppressing Iranian nationalism. There are bitter memories of the part “Little Satan” played alongside America’s “Great Satan” in inglorious acts such as the coup against the elected government of Mohammed Mossadegh by MI6 and the CIA in the 1950s.

The killing of Major General Soleimani, the leader of the Quds Force of Iran’s Revolutionary Guards Corps (IRGC), is by most definitions an act of war.

One of the reasons given for the lethal attack by the Trump administration was the death of an American security contractor in a rocket attack on an Iraqi military base in Kirkuk. Just think what would have been justified under this reasoning if the Iranians had killed the chairman of the joint chiefs of staff – the head of the US military.

“A forceful revenge awaits the criminals who have his blood and the blood of the other martyrs last night on their hands” Ayatollah Ali Khamenei, Iran’s supreme leader, has declared. Iran needs to seek retribution, not just because a failure to react would be humiliating, but because its enemies in Sunni Gulf states would see it as a sign of weakness which they could exploit with military action of their own. Also, it is a fundamental principle that a nation state protects its leadership.

However, retaliation through conventional warfare is highly unlikely. It is true that Iran’s military is much more powerful than those of other states the US has been in conflict with recently, such as Gaddafi’s Libya, Saddam Hussein’s Iraq or the Taliban in Afghanistan.

But this needs to be put into context. The US defence budget is 50 per cent larger than Iran’s entire economy, with its GDP of $454bn (£347bn). Iran’s military spending is $14.5bn. In comparison Saudi Arabia spends $69.4bn, the UAE $22.8bn, Israel $16.4bn and Turkey $18.2bn.

Iran has become militarily closer to Russia and China. The three countries held highly-publicised naval manoeuvres in the Gulf last week. But judging by what happened with Libya and Iraq, one cannot see Moscow or Beijing getting engaged in a military conflict with the US.

However, conventional warfare is not the only method of modern aggression, with great focus now on asymmetric warfare. Cyber capabilities are a hugely important part of this weaponry, and Iran not only has the capability but the form for deploying it.

Iran was blamed for targeting Wall Street banks with denial of service attacks in 2012, knocking their websites offline in retaliation against US sanctions. In 2015, Turkey blamed Tehran for cyberattacks which hit its electricity grid, shutting down power for 40 million people. Two years ago dozens of parliamentary accounts in the UK were breached in attacks linked to Iran. Earlier this year Tehran was blamed for data hacking from a number of American businesses.

Sam Curry, chief security officer at Cybereason, a US-based computer security firm founded by former members of the Israeli military’s storied cyber-wing, pointed out that as with any form of asymmetric warfare, not knowing where the strike will land is the real issue.

“They’re not going to start developing now the attacks that they’ll use, they have developed them already,” he said. “It could be military, could be civilian – the initiative now lies with Iran to pick and choose among the options they have. Will they retaliate in kind? Send a message of escalation? The question is, what and where and when?”

In any event by its very nature cyberwarfare aimed at targets like the financial system are not necessarily nation-specific. A hit on an American bank at commercial hubs like the City of London and Frankfurt would have a highly damaging ripple effect.

Iran’s capabilities are not just technical. It can call upon allied militias – in Lebanon, Yemen, Iraq and Syria – to strike at American targets and those of its partners in the region. The militias in Iraq will be particularly highly-motivated given that Abu Mahdi al-Muhandis, one of their most senior commanders, was killed in the strike along with Soleimani. Allied troops, from Britain and other western countries, could easily get caught up in assaults.

Iran, or Iranian-backed groups, have carried out clandestine operations outside the region in countries in the Americas, Asia and Europe, including against exiled dissidents in the UK. A plot to blow up the Saudi ambassador in Washington was foiled in 2011, which the US said was “a deadly plot directed by factions of the Iranian government”. Tehran called the claims baseless.

Supposing attacks were carried out against American targets in London, would a post-Brexit Boris Johnson government, detached from the European Union, dependent on the Holy Grail of a trade deal with the US, be able to resist pressure from the Trump administration to take severe punitive action against Iran? And what would be the Iranian reaction to that?

It is possible, of course, that the US and Iran will, against expectation, draw back from the brink of another round of bloodshed, although it is very difficult to see how. It is also difficult to see how other countries can remain detached and unscathed if and when the turmoil begins.