In a broadside against his Nato partners, the US president said nations across Europe, including the UK, France and Germany, had been a “tremendous disappointment” for not repatriating individuals imprisoned in Syria.
He said: “I actually said to them, ‘If you don’t take them, I’m going to drop them right on your border. And you can have fun capturing them again’.”
Ross Greer, the Scottish Green external affairs spokesman, condemned the remarks, made by Mr Trump during a press conference announcing the killing of IS leader Abu Bakr al-Baghdadi.
He said those being held were “far too dangerous to be used as political footballs by someone as ignorant as Donald Trump”.
Mr Greer said: “The ‘special relationship’ between the UK and the US has been toxic for decades, but now even that lies in tatters.”
Pointing to the US decision to pull back from Turkey’s border with Syria after the Turkish president Recep Erdogan decided to unilaterally launch an operation to create a so-called “safe zone”, Mr Greer said that “no-one has done more in recent weeks to bring about a resurgence of IS” than Mr Trump and Mr Erdogan.
He went on: “There are only two responsible options for the thousands of former ISIS members currently held by the Syrian Democratic Forces.
“Either the nations they have come from, the UK and US included, take responsibility for prosecuting their own citizens or we convene an international court on the same basis as was done for the criminals in the former Yugoslavia.”
The move by Mr Trump to largely turn his back on Syrian Kurds who fought IS has drawn widespread global criticism. Mr Greer described it as a “catastrophic betrayal” that paved the way for a Turkish campaign of “ethnic cleansing”, with hundreds of IS members escaping amid the “chaos”.
Downing Street has said the UK government will continue to seek justice for foreign fighters in the region where their crimes took place.
It comes as a UN official said evidence seized by troops at Baghdadi’s compound will hopefully help future prosecutions of those accused of “heinous acts” committed in the name of IS.