A year after France mounted Operation Serval to rid northern Mali of jihadists, they seem to be back. According to local sources but also the security forces, jihadists have regained a foothold in several areas.

Islamists have pressured families hostile to their presence to leave their homes. Over the past six months al-Qaida in the Islamic Maghreb (AQIM) has murdered several people who helped the French military in Mali, in particular Touareg members of the National Movement for the Liberation of Azawad (MNLA). At least 10 people have been killed.

There is also growing concern at the repeated attacks by suicide bombers or with mines and small arms on French, Chadian and Malian forces despite the presence of 6,000 troops from the United Nations Stabilisation Mission in Mali (Minusma) on the ground.

On 20 February a French helicopter on a reconnaissance mission near Tessalit was hit by ground fire and a crew member was injured. The aircraft was able to land safely but rumours that it had crashed spread through Bamako.

Three groups are involved in the insurrection in northern Mali: AQIM; the Movement for Unity and Jihad in West Africa (Mujao); and Ansar Dine, led by the Touareg Iyad Ag Ghaly. The latter group are the most visible in the field, concentrated in their traditional sphere of influence, north of Kidal, close to the border with Algeria. At the beginning of February the population of Boughaessa was told that it must either show its support or leave. Several families fled the village.

Later that month, according to a local source, Sheikh Ag Awissa, aka Abu Muhammad, and other Ansar Dine cadres summoned residents and explained they would be keeping a low profile with regard to the French forces, but would nevertheless be increasingly active.

Extending his sphere of action, Ghaly is recruiting young people and stockpiling provisions from across the border. He is also taking advantage of tensions among local tribes, in particular the Irayakan and Telkatana, to tighten his grip.

Meanwhile his AQIM allies are busy attacking MNLA positions on the border. They recently mounted an assault on Talahandak, a town used to conceal weapons, vehicles and equipment.

On the Algerian side, Tinzaouaten is an important rear base for Ansar Dine and other Islamist groups. Ghaly, who has allegedly built a house here, was spotted a fortnight ago before returning to Libya. But members of his staff and his wife, Anna walet Bicha, are thought to live here permanently. The part of the settlement on the Malian side of the border is divided between supporters of MNLA and Ansar Dine.

At nearby Abeyra, Ansar Dine decided in February to organise patrols by Islamic police. It also handed out money to local residents. Meanwhile, Islamists in the Oukenek area made contact with local supporters and established what the military call "forward positions" from which to attack Minusma convoys.

AQIM units have been spotted at Telakak, 65km south-east of Tessalit, to the north of the Adrar Tigharghar hills. They were also seen at Bakasso, to the east of these hills. The Dorayat valley is thought to be one of their hideouts.

Further west, Mujao Islamists suddenly appeared at Djebock, near Gao, raised their flag and set up roadblocks. Then they vanished again. The same group was probably responsible for firing several rockets at Gao.

"The return of the jihadists is emblematic of the failure of French and international strategy," says MNLA spokesperson Moussa Ag Acharatoumane. "We have always said that the only solution is political." The French military, currently centralising its regional command in Chad, rejects this claim. "We have put an end to terrorism on an industrial scale; all that remains are sporadic incidents," a Le Monde source asserted.

Pierre Boilley, a specialist on the Sahel, thinks the jihadists "have just changed their organisation". "The biggest source of concern," he adds, "is the political deadlock in negotiations between the government in Bamako and movements in northern Mali, which facilitates the jihadists' return. Time is on their side, too."

This article appeared in Guardian Weekly, which incorporates material from Le Monde