Around 800 Isis fighters of European origin are currently being detained in northern Syria by the US-backed Syrian Democratic Forces, along with thousands of women and children.
The Trump administration has been pressuring EU governments to repatriate their citizens suspected of joining Isis, but most have been reluctant to do so, fearing they would present a security risk upon their return.
“We have thousands of Isis fighters that we want Europe to take and let’s see if they take them. And if they don’t take them, we’ll probably have to release them to Europe,” Mr Trump said on the White House lawn on Thursday.
The SDF is thought to be holding around 13,000 foreigners suspected of Isis links — not including Iraqi or Syrian fighters. That number is made up of 2,000 men and 11,000 women and children, most of whom were detained when the terror group’s caliphate fell earlier this year.
More than 50 British citizens are thought to be detained, including nine men, 20 women and around 30 children. Shamima Begum, who fled her home in Bethnal Green aged 15 to join Isis in Syria, is among them.
Mr Trump appeared to conflate the European fighters with Isis members from other countries in his comments on Thursday, claiming there were “2,500 Isis fighters that we want Europe to take, because they were going back into Europe, into France, into Germany, into various places.”
The president was responding to a question from reporters about Tulsi Gabbard, a Democratic congresswoman from Hawaii running for the White House in 2020.
It is not the first time Mr Trump has threatened to release European Isis fighters held in Syria. Back in February, when the Isis caliphate was close to collapse, he called on “Britain, France, Germany and other European allies to take back over 800 Isis fighters that we captured in Syria and put them on trial.”
“The caliphate is ready to fall. The alternative is not a good one in that we will be forced to release them,” he wrote on Twitter.
The SDF, the US-backed militia that is holding the suspects, has said it does not have the capability to continue holding them indefinitely. It has proposed setting up an international tribunal to try the Isis suspects.
But such a court would need the backing of the United Nations Security Council, and would likely be blocked by Russia on behalf of its ally, the Syrian government, which sees the SDF as a threat to its rule.
In the meantime, US military leaders have warned that the next generation of jihadis was being raised in Syrian camps holding the families of Isis members.
In an exclusive interview with The Independent, Major General Alexus Grynkewich, deputy commander of the international coalition to defeat Isis, described the potential for radicalisation in the camps as “the biggest long-term strategic risk” in the fight against the jihadi group outside of ongoing military operations.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies