Senior former commanders in the British military have condemned the way Kurdish allies in Syria have been abandoned by Donald Trump, and have spoken of their deep concern about how the move has raised the threat of Isis rising again to carry out attacks in the region and beyond.

The generals, most of whom have taken part in missions in the Middle East and Afghanistan, also point out that the US withdrawal from Syria, which in turn forces other western troops to depart, has left a security vacuum open to pervading Russian and Iranian influence.

The views of the eminent senior officers, expressed to The Independent, are in contrast to that of the defence secretary Ben Wallace, who has faced strong criticism from western allies after attempting to justify Turkey’s military offensive in northern Syria by claiming it was essentially a defensive measure.

Turkey last Wednesday launched “Operation Peace Spring”, after Trump effectively greenlit the move by announcing the withdrawal of US troops from northern Syria. The Turkish offensive has attracted global condemnation, amid fears of a humanitarian crisis.

Hundreds of thousands of Syrians have become internally displaced, dozens of civilians have been killed and hundreds of detainees have escaped from Kurdish camps and prisons – some of them relatives of Isis members – since the offensive began.

Turkey launches offensive into Syria Show all 25 1 /25 Turkey launches offensive into Syria Turkey launches offensive into Syria Turkish soldiers with armored vehicles EPA Turkey launches offensive into Syria A woman flees with her children during Turkish bombardment on Syria's northeastern town of Ras al-Ain AFP/Getty Turkey launches offensive into Syria Smoke billows following Turkish bombardment on Syria's northeastern town of Ras al-Ain in the Hasakeh province along the Turkish border on October 9, 2019. - Turkey launched an assault on Kurdish forces in northern Syria with air strikes and explosions reported along the border. President Recep Tayyip Erdogan announced the start of the attack on Twitter, labelling it "Operation Peace Spring". (Photo by Delil SOULEIMAN / AFP) (Photo by DELIL SOULEIMAN/AFP via Getty Images) DELIL SOULEIMAN AFP/Getty Turkey launches offensive into Syria The first group of Turkish infantry prepare to enter Syria on the border Getty Turkey launches offensive into Syria Civilians flee AFP/Getty Turkey launches offensive into Syria Smoke billows from targets inside Syria AP Turkey launches offensive into Syria Turkish armoured vehicles enter Syria in Akcakale Getty Turkey launches offensive into Syria Civilians leave as smoke rises from Ras al-Ain AFP Turkey launches offensive into Syria A multi-rocket launcher fires in an unknown location Turkish Defence Ministry via Reuters Turkey launches offensive into Syria People wave as Turkish soldiers prepare to cross the border Getty Turkey launches offensive into Syria Girls stand together in Ras al Ain town Reuters Turkey launches offensive into Syria A woman walks as smoke billows following Turkish bombardment in Syria's northeastern town of Ras al-Ain AFP/Getty Turkey launches offensive into Syria A Turkish army's tank drives down from a truck towards the border with Syria AFP/Getty Turkey launches offensive into Syria Turkish jet taxis on tarmac after returning to a military base in southeast Diyarbakir Reuters Turkey launches offensive into Syria A Turkish armored vehicle drives down a road during a military operation in Kurdish areas of northern Syria EPA Turkey launches offensive into Syria People sit on belongings at a back of a truck as they flee Ras al Ain town Reuters Turkey launches offensive into Syria Turkey-backed Syrian opposition fighters enter Tel Abyad AFP/Getty Turkey launches offensive into Syria Civilians flee AFP/Getty Turkey launches offensive into Syria People flee Tal Abyad North Press Agency/Reuters TV Turkey launches offensive into Syria People wave as Turkish soldiers prepare to cross the border into Syria Getty Turkey launches offensive into Syria Civilians flee with their belongings AFP/Getty Turkey launches offensive into Syria Civilians flee during Turkish bombardment on Syria's northeastern town of Ras al-Ain in the Hasakeh province along the Turkish border on October 9, 2019. - Turkey launched a broad assault on Kurdish-controlled areas in northeastern Syria today, with intensive bombardment paving the way for an invasion made possible by the withdrawal of US troops. (Photo by Delil SOULEIMAN / AFP) (Photo by DELIL SOULEIMAN/AFP via Getty Images) DELIL SOULEIMAN AFP/Getty Turkey launches offensive into Syria Turkish President Recep Tayyip Erdogan, right, speaks with Defense Minister Hulusi Akar, left, as they watch the operation by Turkish forces in Kurdish areas EPA Turkey launches offensive into Syria Smoke rises from the Syrian town of Tal Abyad AFP/Getty Turkey launches offensive into Syria Turkey-backed members of Syrian National Army prepare for moving to Turkey with heavy armed vehicles EPA

A meeting of the Nato Parliamentary Assembly in London heard on Monday, with surprise and consternation, Mr Wallace say that: “Turkey needs to do what it has to do to defend itself. It is absolutely clear that Turkey has a threat emanating towards it from groups such as the PKK, a terrorist organisation.”

A member of the German Bundestag spoke of his astonishment at Mr Wallace’s remark and pointedly asked: “If you are convinced that Turkey has a legitimate reason for invading Syria, what would be your answer to the Turks if they were to ask you, in reference to Article 5 [which stipulates mutual support for Nato members] that Nato should support them?”

UK and other European special forces, present in limited numbers in Syria, had been working alongside the Americans, with the Kurdish-led Syrian Defence Force (SDF). They have now withdrawn from northern Syria and will leave the country when US troops do so.

The Kurds on Sunday signed a security deal with Damascus, hoping to push back the Turkish offensive. Kurdish dreams of an autonomous statelet appear to be over.

There is, The Independent understands, a feeling of great unhappiness among many involved in the British and US mission to Iraq and Syria about what has unfolded.

General Sir David Richards, the former head of the British military, and former commander of international forces in Afghanistan, told The Independent that: “On an emotional level, and certainly from a tactical perspective, what is being done to the Kurds is plainly wrong.

"In fact it’s pretty awful after all they have done against Isis on our behalf. But more importantly, the region as a whole continues to suffer from the absence of a clear and coherent western strategy."

He added: “Decisions have been taken by the Trump administration that are very difficult to fathom. At one level, we do not know what’s going to happen now to a bunch of very violent Isis prisoners. Are they going to become free again to carry on terrorist attacks? At another level these decisions also mean that Russian and Iranian influence will grow. I really can’t see how any of this protects or enhances Western interests. It’s quite the opposite.”

General Sir Richard Barrons, the former chief of Joint Forces Command, who had served in Northern Ireland, Iraq and Afghanistan, lamented that Trump’s decision has pushed the Kurds to turn to the Assad regime for support.

“The move by President Trump to withdraw US forces was used by the Turks to go into Syria in the guise of a CT [counter terrorist] operation to attack who they see as their Kurdish enemy, and create a zone where they are going to put some of the millions of Syrian refugees in their country,” Sir Richard said.

Ankara sees Syrian Kurdish groups as an extension of the PKK, a group banned in Turkey.

The American move, Sir Richard said, “has meant that the SDF has been suddenly left without support and this means they have had to turn to the Syrians”.

With the Kurds it is a matter of treating allies with decency and honour. The Kurds did a good job against Isis, and this is not the way they should have been treated Major General Julian Thompson, former Commandant General of the Royal Marines

“We will have to see just what terms Assad imposes on them – probably not very pleasant. The question we have to ask is what will others we will want as allies against a common enemy think of us? Would they think of the west as a reliable partner after this?

“You have also got the question of Isis prisoners. A few of them will be taken to America, although we hear that the US forces were not able to get many of the ‘high-value’ ones because of the way the withdrawal took place.

“What’s going to happen to the others? Of course if like Britain you strip them of citizenship you can’t bring them back for trial. We know some of them have already escaped, with the Kurds focusing on the Turkish operation.”

On Sunday, nearly 800 detainees, many of them relatives of Isis members, escaped from Ain Issa camp in northern Syria, as Kurdish guards left for the frontline.

“Are these people going to face justice anywhere, or are these very dangerous people going to be turned out into the wild, to carry out attacks in Europe?” Sir Richard asked.

But Major General Tim Cross, a Balkans and Iraq war veteran, believes that the US would have probably faced criticism whatever action it took.

Pro-Kurdish protesters march in London against Turkish military campaign in Northern Syria

“If it decided to reinforce in Syria then America would have been accused by some of being bloodthirsty, of being imperialistic.

“I think a lot of people in America want an end to foreign wars and Trump has tapped into it, he seems very determined to get out of them,” he said.

“I think what we are seeing here is a great division in western views. There are people in Paris and Berlin who say they simply cannot work with Trump. And then you hear people in America who complain about Europe not spending enough in defence, and on terrorism, it’s Europe which is the target, and they say Europe should take the lead in dealing with it. This is a worrying division which probably won’t be solved for the time being.

“As for the Kurds, there are some good, some bad. But it’s obvious what has happened in this case – the fighters we have been working with have been used against Isis, and then they have been hung out to dry.”

Major General Julian Thompson, the commandant general of the royal marines during the Falklands, said that: “There is obviously a Turkish viewpoint on this. But the way they are going about things have opened them up to a lot of criticism.