General Francois Lecointre said France’s military role in the Sahel region south of the Sahara was “useful, good and necessary”, but it was hard to see the moment when the war would finally be won.

The remarks could embolden opponents of President Emmanuel Macron, in particular on the far-left, who are demanding France plots a way out of the conflict.

“We will never achieve a definitive victory,” Lecointre, chief of staff of the armed forces, told France Inter radio.

The 13 French soldiers were killed in Mali on Monday when two helicopters collided in the dark after being called in to provide air support during a combat mission to track down a band of Islamic State militant fighters.

One source said the operation was in reaction to an attack in Indelimane, Menaka region, in late October that killed at least 53 Malian soldiers and was claimed by Islamic State.

France intervened in Mali in 2013 to repel insurgents advancing out of northern strongholds into central Mali. There are now 4,500 French troops in the wider region, as part of “operation Barkhane”, named for a crescent-shaped sand dune.

However, Islamist militants linked to al Qaeda and Islamic State have strengthened their foothold. Swathes of the arid Sahel region are ungovernable.

“We’re getting results but we have to be patient and persevering,” Lecointre said.

The two black boxes from the Tiger attack helicopter and the Cougar multipurpose helicopter have been recovered, military officials said, and will be central to the investigation into how the accident occurred.

The defense minister, Florence Parly, arrived in Mali to pay tribute to the soldiers who died. France hopes to repatriate the soldiers’ bodies in the days ahead.

Ground commandos had been tracking the group of militants through harsh terrain for several days before making contact on Monday in the Valley of Eranga, central Mali. Air support was called in after a gun-battle erupted.

One local resident described the region where the collision occurred as lawless and overrun by jihadists.

“We call it the red zone. No-one dares wander that way,” the resident said, declining to be identified for fear of retribution.

The area has been a focal point for recent French operations against Islamic State affiliated militants, according to Menastream, a risk consultancy group that monitors jihadist activity in the region.

France has complained to European allies that it is bearing the brunt of a counter-terrorism operation that benefits all Europe.

In June, amid a spike in militant attacks, France urged European powers to provide special forces to support the G5 Sahel force – made up of thousands of soldiers from Mali, Niger, Burkina Faso, Chad and Mauritania – as it struggled to contain a rise in violence.

Commitments so far had been minimal and the deaths of the French troops would not encourage more, one western diplomat in West Africa said.

“No European government is keen on body bags,” the diplomat said.

REUTERS