BAGHDAD: Iraqi forces Friday launched an assault on the northern town of Hawijah, one of the last bastions in the country still held by Daesh (ISIS), which is also under attack in neighboring Syria. The operation came after Daesh released what it said was an audio recording of its leader Abu Bakr al-Baghdadi urging resistance, the first such intervention in nearly a year.

“The leaders of the Islamic State [Daesh] and its soldiers have realized that the path to ... victory is to be patient and resist the infidels whatever their alliances,” the voice in the recording said, whose authenticity Washington said it had “no reason to doubt.”

Since Baghdadi’s previous message to his followers last November, the territory the militants still hold in the cross-border caliphate they proclaimed in 2014 has shrunk to a fraction of its former extent.

“A huge military operation has begun to liberate Hawijah and its surrounding areas,” the operation’s commander, Lt. Gen. Abdel-Amir Yarallah, said in a statement.

Iraqi forces launched an offensive to retake the militant enclave around Hawijah on Sept. 21, swiftly taking the town of Sharqat on its second day before pushing on toward Hawijah itself.

Yarallah said that Friday’s assault marked the second phase of the operation and aimed to recapture Hawijah and the towns of Al-Abbasi, Riyadh and Rashad to its west, east and south.

All are mainly Sunni Arab towns that have long been bastions of insurgency and were bypassed by government forces in their push north on second city Mosul last year which culminated in the militants’ defeat in their most emblematic stronghold this July.

Yarallah said troops were now advancing on the town of Al-Abbasi.

He said the operation involved the army, the federal police, counterterrorism units and the Rapid Intervention Force, as well as tribal volunteers and the paramilitary Al-Hashd al-Shaabi forces mainly made up of Iran-trained Shiite militia.

The enclave lies east of the Tigris River and south of one of its major tributaries, the Little Zab. Troops erected pontoon bridges during the night to enable the assault to begin, Yarallah said.

Al-Hashd al-Shaabi said that Daesh had set fire to two oil wells in the Alas field, southeast of Hawijah, in a bid to provide cover and slow the advance of loyalist’s forces.

Iraqi Prime Minister Haider al-Abadi hailed the second phase of the operation to recapture the area.

“As we promised the sons of our country, we are going to liberate every inch of Iraqi land and crush the Daesh terrorist gangs,” Abadi said.

“We are on the verge of a new victory to liberate the residents of these areas from those criminals.”

Separately, Iraqi forces discovered a mass grave near Tal Afar, some 70 kilometers west of Mosul, containing dozens of bodies of Daesh fighters probably killed in an airstrike, officials said.

“It’s the first mass grave of this kind to have been discovered” near Tal Afar, local official Abdel-Aal Abbas said.

The names of the militants and when they were killed appeared on memorial plaques near the grave, another security source said.

Meanwhile, the U.S. military said Friday it has confirmed an additional 50 civilians killed by U.S. coalition air or artillery strikes in Iraq and Syria.

That raises the total number of civilians assessed to have been unintentionally killed by the coalition since August 2014 to 735.

In its monthly update on civilian casualties in the war against Daesh, the coalition said that in August it completed its assessment of 185 reports of civilian casualties, including from previous months. Of the 185, only 14 were deemed credible, resulting in 50 deaths.

The most recent fatalities happened July 14 when 10 civilians were killed in a strike on a Daesh tunnel system in Mosul.

In each case, the military said all feasible precautions had been taken to avoid harming civilians.

The coalition also said at least 1,200 Iraqi security personnel were killed during the operation to recapture Mosul.

“The October 2016 to July 2017 battle to liberate Mosul reflects a significant sacrifice by our Iraqi partners, who lost 1,200 to 1,500 personnel in action, with an approximate 8,000 more wounded,” the coalition said in a statement.

It did not provide a breakdown of casualties among the various forces that took part in the grueling battle.