Syria’s U.S.-backed Kurdish-led force has handed over to Baghdad two Islamic State group militants suspected of involvement in mass killings of Iraqi soldiers in 2014, a war monitor said Friday.

The report by the Syrian Observatory for Human Rights came a day after the Iraqi National Intelligence Service said it had brought back to the country three IS members from outside Iraq. The intelligence service did not provide more details.

The Islamic State group captured an estimated 1,700 Iraqi soldiers after seizing Saddam Hussein’s hometown of Tikrit in 2014. The soldiers were trying to flee from nearby Camp Speicher, a former U.S. base.

ISIS CLAIMS RESPONSIBILITY FOR BOMBING THAT KILLED A DOZEN POLICE OFFICERS IN AFGHANISTAN

Shortly after taking Tikrit, IS posted graphic images of IS militants shooting and killing the soldiers.

Farhad Shami, a spokesman for the Kurdish-led Syrian Democratic Forces, said the U.S.-backed force handed over two IS members to Iraq. It was not immediately clear where Iraqi authorities brought the third suspect from.

The 2014 killings, known as the Speicher massacre, sparked outrage across Iraq and partially fueled the mobilization of Shiite militias in the fight against IS, a Sunni extremist group.

Iraq has over the past several years put on trial and later executed dozens of IS members over their involvement in the Speicher massacre.

The Observatory said the two IS members were among 20 captured recently in a joint operation with the U.S.-led coalition in the northern Syrian city of Raqqa, once the capital of the Islamic State group’s self-declared caliphate.

Despite their defeat in Iraq in 2017 and in Syria in March 2019, the extremists sleeper cells are still active and have been carrying out deadly attacks against SDF and Syrian government forces.

Shami said a car rigged with explosives and driven by a suicide attacker tried Friday night to storm a military checkpoint for the Deir el-Zour Military Council, an Arab majority faction that is part of the SDF, in the eastern Syrian village of Shuheil. Shami said that when the guards tried to stop the car, the attacker blew himself up killing three U.S.-backed fighters.

No one immediately claimed responsibility but the attack but it was similar to previous such explosions carried out by IS militants.

The SDF is holding over 10,000 captured IS fighters in around two dozen detention facilities, including 2,000 foreigners whose home countries have refused to repatriate them. The force says fighters of about 60 nationalities had entered Syria years ago and were captured in battle.

Kurdish authorities in northeastern Syria have said they will put on trial IS detainees, though it is not clear when such trials would begin.

British-Israeli Nadav Popplewell was taken captive from Nirim kibbutz by Palestinian group Hamas on October 7.

Hamas’s armed wing, the Qassam Brigades, has said British-Israeli captive Nadav Popplewell died of wounds sustained in an Israeli air strike a month ago.

The group’s announcement on Saturday came just hours after the Palestinian group released an 11-second video showing Popplewell with a bruised eye.

In the video republished on social media and cited by Israeli news outlets, a man is seen wearing a white T-shirt and he introduces himself as 51-year-old Nadav Popplewell from the Nirim kibbutz in southern Israel.

Superimposed text in Arabic and Hebrew reads: “Time is running out. Your government is lying.”

Popplewell was taken captive in Nirim during the Hamas-led attack on October 7, according to Israel’s Ynet news site. His mother was also taken as a captive but later released during the exchange of captives and prisoners by Hamas and Israel last year. Popplewell’s brother was killed in the attack, Ynet reported.

The video posted on Saturday on the Telegram channel of Hamas’s armed wing is the third time in less than a month the group has released footage of captives held in Gaza.

On April 27, Hamas released a video showing two captives alive – Keith Siegel and Omri Miran. Three days earlier it also broadcast another video showing captive Hersh Goldberg-Polin alive.

The videos come amid growing domestic pressure on the Israeli government to secure the release of the remaining captives.

Reporting from Amman, Al Jazeera’s Stefanie Dekker, said this tactic of releasing videos of captives on a Saturday, when protests take place in Tel Aviv, is a way of pressurising the Israeli government.

“This is what’s been a drip-feed if you will from Hamas. Where, by releasing videos, at times showing hostages dead, they are trying to put pressure on the Israeli government,” she said.

“But this hasn’t really changed the policies of [the Israeli] government.”

On Saturday, the Hostages and Missing Families Forum in Israel released a statement calling on the Israeli government to strike a deal with Hamas in order to secure the release of captives.

“Every sign of life received from the hostages held by Hamas is another cry of distress to the Israeli government and its leaders,” the families’ group said in its statement.

“We don’t have a moment to spare! You must strive to implement a deal that will bring them all back today.”

Relatives of the captives also accused Prime Minister Benjamin Netanyahu of not caring about those being held in Gaza and called on Netanyahu to resign.

“There is no victory and can be no victory without the return of the hostages,” a spokesperson said at a press conference in Tel Aviv on Saturday afternoon.

Despite the immense pressure, Netanyahu and his government have so far failed to strike a deal with Hamas.

Some 1,139 people were killed on October 7 when Hamas and allied fighters attacked southern Israel, and 250 captives were also taken to the Gaza Strip. Israeli officials say 128 of them are still being held in the Palestinian territory, including 36 who are dead.

Israel’s seven-month military campaign in Gaza has so far killed at least 34,971 people and wounded 78,641 others.