Experts believe failure to inflict casualties was deliberate and is sign overt conflict is ending

The overt phase of the conflict between Iran and the US is probably over, British sources believe, because Tehran appeared to have chosen to miss when it failed to inflict any casualties with the missiles and rockets it fired at two military bases in Iraq.

The judgment is that the attack on bases housing US troops in the early hours of Wednesday was demonstrative, given that the Iranian missiles used were believed to be accurate to a range of 50 metres and could have caused more serious damage if Tehran had wanted to.

A warning from Iran also meant that coalition forces knew in time that the missiles were incoming and that steps could be taken to avoid casualties as the al-Asad and Erbil bases. “People had enough time to take cover,” a defence source said.

However, the concern remains that Iran will order a more deadly covert response in the future, reflecting that a belief that despite the US killing of the senior Iranian general Qassem Suleimani, the regime in Tehran remains in the control of hardliners.

For now there remains considerable relief in British circles that an extended conflict appears to have been averted after Donald Trump signalled on Wednesday that no military action would be taken in response to the overnight rocket attack.

Defence sources said Trump had briefed Boris Johnson on the contents of his statement in a phone call earlier on Wednesday afternoon, to reassure the UK that immediate military action was off the table.

There were a handful of British troops based in Erbil, the capital of the Kurdish region of Iraq, alongside American forces. UK personnel moved out of the al-Asad base last year, the Ministry of Defence said earlier on Wednesday.

Earlier, Johnson strongly backed the US’s decision to kill Suleimani in a missile strike, telling prime minister’s questions that while he could not comment on the legality of the act, “most reasonable people” would think the operation was justified.

Making his first parliamentary appearance of the year, the prime minister condemned the Iranian response, and called for calm.

Jeremy Corbyn told PMQs that the US attack had greatly destabilised the region, accusing Johnson of being “unable to stand up to President Trump” because of his need for a swift post-Brexit trade deal with the US.

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Johnson began by condemning the Iranian strikes, which did not kill or injure any coalition forces. “Iran should not repeat these reckless and dangerous attacks but must instead pursue urgent de-escalation,” he said.

Asked by Corbyn whether he would oppose “any further retaliation or escalation in violence”, the PM confirmed he would, pointing to joint European calls for calm and saying he was “working solidly” with allies over this.

Johnson’s remarks followed foreign secretary Dominic Raab describing the Iranian retaliatory strikes as “reckless and dangerous” and calling on Tehran “to pursue urgent de-escalation”.

At PMQs, Corbyn asked Johnson if he believed that the US operation to kill Suleimani was permitted under international law.

Johnson replied: “Clearly the strict issue of legality is not for the UK to determine, since it was not our operation. But I think most reasonable people would accept that the United States has a right to protect its bases and its personnel.”

The PM further defended the operation, saying Suleimani had been a long-time instigator of violence in the region and had “the blood of British troops on his hands”.

Timeline The buildup to Qassem Suleimani's death Show Hide A rocket attack on an Iraqi military base near Kirkuk kills an American contractor and injures US and Iraqi soldiers. The US blames Shia militia group, Kata’ib Hizbullah (KH) The US conducts retaliatory airstrikes against five KH bases in Iraq and Syria, saying there had been 11 attacks against Iraqi bases hosting coalition forces in Iraq over the past two months Protesters storm the US embassy in Baghdad, trapping diplomats inside while chanting “Death to America” and slogans in support of pro-Iranian militias. At one point they breached the main gate and smashed their way into several reception rooms. The rampage was carried out with the apparent connivance of local Iraqi security forces who allowed protesters inside the highly protected Green Zone In a drone strike ordered by US president Donald Trump, the US kills Iranian general Qassem Suleimani while he was being transported from Baghdad airport

Corbyn said he was not convinced by this argument: “If we stand by international law, as I’m sure the government does and would want to, then surely killing somebody in a foreign territory is an illegal act and should be condemned as such. If we believe in international law, that should be the solution to the problems in the world.”

The Labour leader went on to condemn the US killing, and to say that Johnson was unable to challenge Trump on his actions.

“This government’s response is not putting the interests of this country first, but instead seems more interested in prioritising the prime minister’s relationship with President Trump over the security of the region and of this country.

“Isn’t the truth that this prime minister is unable to stand up to President Trump because he has hitched his wagon to a trade deal with the United States?”

Johnson responded by calling this “absolute fiction”. He added: “But what I will say is that the UK will continue to work for de-escalation in the region.”