The foreign secretary has backed Donald Trump’s “right” to assassinate Iran’s top military general, in a marked shift towards supporting the incendiary attack.

Dominic Raab said the UK “understands the position the US found themselves in” ahead of killing Qasem Soleimani, saying it had “a right to self-defence”.

Mr Raab also declined to criticise the US president’s overnight threat to hit 52 Iranian sites if Tehran retaliates for the assassination – in what would appear to hint at looming all-out war in the Gulf.

He said he saw it as “the Americans trying to send a very clear message to Tehran that it cannot continue its menacing behaviour”.

However, the foreign secretary again called for both sides to “de-escalate”, saying a war would benefit no one but Isis, which would “exploit the vacuum”.

Speaking on Sky News, Mr Raab refused to comment on whether UK troops in Iraq were being switched from training local forces to “force protection”, because of the heightened threat.

He also declined to say whether Britons in the Middle East were now at greater risk, but confirmed that military escorts of UK shipping in the Gulf had been restored.

Asked whether the US was “right” to carry out the assassination, Mr Raab replied: “The US will take their own operational judgement call, but they’ve got the right of self-defence.

US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Show all 35 1 /35 US airstrike kills Iran's Qassem Soleimani: Fallout in pictures US airstrike kills Iran's Qassem Soleimani: Fallout in pictures This photo released by the Iraqi Prime Minister Press Office shows a burning vehicle at the Baghdad International Airport following an airstrike in Baghdad, Iraq, early Friday 3 January AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures The wreckage of the car in which general Soleimani was travelling when a targeted US airstrike struck outside Baghdad International Airport on 3 January Ahmad Al Mukhtar via Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Demonstrators burn the US and British flags during a protest in Tehran after general Soleimani was killed in a targeted airstrike by American forces Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A burning vehicle at the Baghdad International Airport following an airstrike. The Pentagon said Thursday that the US military has killed general Qassem Soleimani, the head of Iran's elite Quds Force, at the direction of Donald Trump AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters burn Israeli and US flags as thousands of Iranians take to the streets to mourn the death of general Soleimani at the hands of America EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Supporters of Donald Trump pray at an 'Evangelicals for Trump' campaign event held on the day following the killing of general Soleimani. At the event, the president praised the "flawless strike that eliminated the terrorist ringleader" AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A huge procession of mourners gather in Baghdad for the funeral of general Soleimani on 4 January AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Thousands of Iranians take to the streets to mourn the death of Soleimani during an anti-US demonstration to condemn the killing of Soleimani, after Friday prayers in Tehran, Iran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iraqis perform a mourning prayer for slain major general Qasem Soleimani of the Iranian Revolutionary Guards at the Great Mosque of Kufa AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A billboard reading 'Death to America and Israel', installed by Iran-backed shiite armed groups at a street in Jadriyah district in Baghdad, Iraq EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A handout picture provided by the office of Iran's supreme leader Ayatollah Ali Khamenei shows him visiting the family of Soleiman KHAMENEI.IR/AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Thousands of Iranians take to the streets in Tehran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Pakistani Shiite Muslims burn a mock of a US flag as they hold pictures of General Qasem Soleimani during a protest against the USA, outside the US Consulate in Lahore, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iran's Ambassador to Lebanon Mohammed Jalal Feiruznia, looks to a portrait of Soleimani, as he receives condolences at the Iranian embassy, in Beirut, Lebanon AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures People make their way on the street while a screen on the wall of a cinema shows a portrait Soleimani in Tehran AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Aziz Asmar, one of two Syrian painters who completed a mural following the killing of Iranian Revolutionary Guards commander Qasem Soleimani poses next to his creation in the rebel-held Syrian town of Dana in the northwestern province of Idlib AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A demonstration in Tehran AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures An anti-US demonstration to condemn the killing of Soleimani, after Friday prayers in Tehran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Mujtaba al-Husseini, the representative of Iran's supreme leader Ayatollah Ali Khamenei, delivers a speech in the holy shrine city of Najaf AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Pakistani Shiite Muslims burn a mock of a US and Israeli flags as they hold pictures of General Qasem Soleimani during a protest against the USA, outside the US Consulate in Lahore, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters demonstrate in Tehran AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Pakistani Shi'ite Muslims hold pictures of General Qasem Soleimani during a protest against the USA, in Peshawar, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters, holding a photograph of the leader of the People's Mujahedin of Iran Massoud Rajavi, outside Downing Street in London PA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters burn a US flag in Tehran AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A Syrian man offers sweets to children to mark the killing AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian worshippers attend a mourning prayer for Soleimani in Iran's capital Tehran AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Kashmiri Shiite Muslims shout anti American and anti Israel slogans during a protest AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian worshipers chant slogans during Friday prayers Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A protest against the USA, in Islamabad, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranians burn a US flag in Tehran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Supporters of the National Council of Resistance of Iran in Germany (NWRI) protest outside Iran's embassy in Berlin, Germany Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Supporters of the National Council of Resistance of Iran in Germany (NWRI) protest outside Iran's embassy in Berlin Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian worshippers in Tehran AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Vehicles of the United Nations Interim Forces in Lebanon (UNIFIL) patrol a road in the southern Lebanese town of Kfar Kila near the border with Israel. Following morning's killing of Major General Qasem Soleimani, Lebanon's Iran-backed Hezbollah movement called for the missile strike by Israel's closest ally, to be avenged AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian women take to the streets in Tehran EPA

“If you look at what General Soleimani was doing, he’s not some victim in this scenario.

“He was a regional menace, he was in charge of the Quds Force, the wing of the Iranian Revolutionary Guard, which is directing militias and proxies in the region, in Iraq, in Lebanon, in Syria which is destabilising those countries, trying to get an Iranian advantage and trying to attacking western countries that are legitimately there.

“So we understand the position the US were in and I don’t think we should be naive about the Iranian Revolutionary Guard or indeed General Soleimani.”

The comments were fiercely criticised by John McDonnell, the shadow chancellor, who tweeted: “Raab’s craven support for Trump’s reckless & potentially disastrous action adds to risk of full scale war.

“A British government must pursue an independent foreign policy in the best interests of our people and to prevent conflict not act as a supine cheerleader for another power.”

Lisa Nandy, a Labour leadership contender, suggested the UK’s refusal to criticise was because it was “begging the US for a trade deal”, as Brexit loomed.

Meanwhile, Emily Thornberry, the shadow foreign secretary, accused Boris Johnson of “sunning himself, drinking vodka martinis” in the Caribbean instead of dealing on the Iran crisis, in a withering attack.

She pointed out that Mark Sedwill, the cabinet secretary, had been left to chair three emergency Cobra meetings about the assassination, in Mr Johnson’s absence.

Mr Raab’s shift to backing the case for the killing was in sharp contrast to the statement he issued on Friday, which inflamed Mr Pompeo – ahead of a meeting between the pair in Washington on Thursday.