Opposition politicians in France have responded with alarm to government confirmation that 130 French jihadists are to be repatriated from Syria.

The controversy emanates from US president Donald Trump’s announcement in December that he will pull 2,000 troops out of north-east Syria, a move that has created an enormous headache for French authorities.

France has deployed about 200 special forces in the same northern zone, which was wrested from the Islamic State terror group by the Kurdish-led Syrian Democratic Forces (SDF).

US forces ferried supplies to French commandos, and the French have relied on US helicopters to evacuate their wounded, Le Figaro has reported. From their aircraft carrier in the Mediterranean, US forces could rescue French troops if they were caught in an ambush or skirmish.

But the 150 French jihadists held by the SDF pose the greatest dilemma. The SDF complains of the burden of guarding 900 foreign jihadists, though France and the UK have compensated the Kurds for holding their citizens.

Fearing abandonment by the US and attack by Turkey, the Kurds have undertaken a rapprochement with their enemy, Syrian president Bashar al Assad, through his Russian allies.

Assad is eager to retrieve the foreign jihadists, for use as bargaining chips. He is playing an intricate diplomatic and intelligence game, typical of the blackmail practiced by his late father, Hafez. If foreign capitals do not re-establish diplomatic relations with Damascus, Assad implies, he will unleash their jihadists. They risk having sleeper cells set up in their home countries, poised to strike at any time.

The UAE has reopened its embassy in Damascus, and is helping the Saudis to deal with Assad, according to Le Figaro’s Middle East expert Georges Malbrunot. Saudi Arabia sent some 5,000 jihadists to Syria to try to topple Assad. Tunisia and Kuwait are also nervous about the return of their fighters.

French interior minister Christophe Castaner. Photograph: Gareth Fuller/PA Wire

France fears the return of the jihadists more than most. About 250 people have been killed in France since 2015 by Islamists with links to the war in Syria. Almost all the killers were French or Belgian.

“We are examining all options to prevent the escape and dispersion of these potentially dangerous persons,” said Agnès von der Mühll, spokeswoman for the French foreign ministry.

Until now, French policy was that citizens who joined Islamic State, also known as Isis, should be tried in Syria or Iraq. But the Kurdish-dominated SDF is not a recognised government. Trials and sentences are not legal under international law. The Iraqi government has sentenced about 100 foreign jihadists to death, which also sits uneasily with Europeans who have ended capital punishment.

So as confirmed by the interior minister Christophe Castaner this week, France is being forced to repatriate about 130 French jihadists. Because France’s relations with Turkey are poor, they are being brought through Iraq, where France also keeps troops.

The numbers could swell. Another 250 French jihadists are reportedly at large in the Syrian Euphrates river valley, near the Iraqi border and in the nortwestern Idlib enclave.

The French right is outraged. Laurent Wauquiez, leader of the conservative Les Républicains (LR), said the “common-sense solution” would be to “simply forbid all those who have left to make jihad from returning”.

Nicolas Dupont-Aignan, the leader of a small far-right party, said the French jihadists should be banished to the Kerguélen islands (overseas French territory, sparsely populated, near Antarctica).

France should rescind their French citizenship, said LR deputy Pierre-Henri Dumont, apparently forgetting that former president François Hollande’s attempt to withdraw citizenship from dual nationals implicated in terrorism was a fiasco. “There’s another choice,” Dumont said. “The elimination of these persons.”

The return of the jihadists is further complicated by the fact that perhaps half of the captured French citizens are children, and half of the adults are women, some of whom are deeply implicated in terrorism. The French justice and prison systems cannot cope with a massive influx of returning jihadists. And if they are tried, it could be difficult to find evidence against them.

French intelligence will have to rely on the electronic records of telephone and social-media networks, financial transfers, videos and whatever information Kurdish and Iraqi allies can provide.

Of 232 returnees from the Iraqi-Syrian theatre, 150 are in prison, Le Figaro reported. But about 30 are due to be freed this year. French intelligence has repeatedly proved unable to prevent individuals on terrorist watchlists from staging attacks.