Egypt hanged 15 men convicted of attacks that killed security forces in the restive Sinai Peninsula, security sources said on Tuesday.

It was the largest mass execution carried out in the North African country since six convicted militants were hanged in 2015.

The men were hanged in two jails in the north of the country where they had been held since military courts sentenced them for the attacks in the Sinai, where militants are waging an insurgency, the officials said.

They were executed early on Tuesday, the sources said.

A military court issued the sentences and Interior Ministry officials carried out the executions simultaneously at Borj Al-Arab and Wadi Al-Natroun prisons, the sources said.

The hangings come a week after Daesh attacked a helicopter with an anti-tank missile at a North Sinai airport as the country’s defense and interior ministers were visiting.

The ministers were unhurt in the attack but an aide to the defense minister was killed along with a pilot.

Most of the militants executed were from Sinai region and were accused of “joining militant groups and taking part in carrying out, planning and assisting in killing a number of army and police personnel in Sinai,” the sources said.

Daesh’s Sinai branch has waged attacks against security forces in a years-long insurgency in North Sinai, and in the past year expanded targets to include Christians and other civilians.

An attack on a mosque last month which killed more than 300 people, the deadliest in Egypt’s modern history, was widely attributed to Daesh, but the group did not claim responsibility for it.

In 2015, six people were executed for killing two soldiers during a raid in Qalyubiah province, north of Cairo.

Daesh’s Egypt affiliate has killed hundreds of policemen and soldiers in attacks in the Sinai and also targeted civilians in the mainland. Egypt has struggled to defeat the militants in the region.

Egyptian courts have sentenced hundreds to death over unrest since the military ousted President Muhammad Mursi in 2013. But most defendants have appealed and won retrials.

While their attacks have become less frequent, they have increasingly targeted civilians over the past year.

In November, suspected Daesh gunmen massacred more than 300 Muslim worshippers at a mosque in Sinai.

The militants have killed more than 100 Christians in church bombings and shootings since December last year.

After the mosque massacre, President Abdel Fattah El-Sisi instructed his military chief of staff to quell the attacks in three months using “brutal force.”

The executions of so many on a single day appears to be a reflection of the government’s recently declared resolve to crush the insurgency following the massacre in the Sinai mosque.

-Agencies