France this week started the pullout from Niger following the overthrow in July of pro-Paris president Mohamed Bazoum which threw French strategy for the region into disarray.

Roughly 1,400 soldiers were based in the capital Niamey and western Niger to battle fighters linked to the Islamic State group and Al-Qaeda, bringing with them fighter jets, drones, helicopters and armoured vehicles -- as well as the equipment to support them.

Now a first contingent has set off from their forward base in Ouallam for neighbouring Chad, travelling by road in armoured vehicles under Nigerien escort for the journey of over 1,600 kilometres (1,000 miles).

Chad's capital N'Djamena is the site of France's military headquarters for the whole Sahel region, with around 1,000 troops deployed there.

From there, French troops can leave by air with their most sensitive equipment.

Some flights -- "up to three per day", according to Nigerien state television -- have also been planned from within Niger for as long as the evacuation continues.

But a French military officer, who asked not to be named, told AFP that returning materiel by air would be "very expensive and require mobilising almost all the transport planes the French air force has".

One A400M transporter can load two containers -- much less than larger Russian or Ukrainian alternatives.

- No easy path -

With more than 2,000 containers' worth of kit on site, most will have to be moved by land and sea, said a former French military logistics specialist in Africa who asked to remain anonymous.

"Most of the equipment will have to go through a deep-water port," he said.

Benin's port of Cotonou would have been the "ideal" choice.

But the border is closed as the government there is at odds with the Nigerien junta.

Many of the French containers will instead be trucked to Douala in Cameroon, several sources familiar with the plans said.

It would be a "long and arduous road" requiring refuelling along the way -- not to mention likely flat tyres and breakdowns on top of the security threats.

- Security risks -

Local sources said the French convoy from Niamey to Chad would travel along Niger's border with Nigeria, passing through towns including Zinder, Diffa and Bosso.

All but a single 100-kilometre stretch of the route is on tarmac road.

But the Diffa region of southeastern Niger has been subject to attacks by Boko Haram and its breakaway arm, Islamic State West Africa Province (ISWAP).

Diffa extends as far as Lake Chad, where the borders of Niger, Nigeria, Cameroon and Chad meet.

The four countries in 2015 set up an 8,500-man force known as FMM to fight jihadist groups.

The rainy season is ending in the area, risking a flare-up in activity by jihadists no longer hemmed in by watercourses, local sources said.

Along its route, the French convoy could also face hostility from the civilian population.

Three people protesting a convoy belonging to the French Barkhane operation in the Sahel were killed during clashes in Tera in western Niger in 2021.

Some local sources blamed the deaths on Nigerian or French troops shooting when the convoy was halted and stoned but the then Niger government said in 2022 a probe had failed to pinpoint the cause.

- Months of work -

French President Emmanuel Macron said in September the military evacuation would be finished "by the end of the year" -- likely a tricky deadline to meet.

Experts believe the operation will last closer to six months.

The route from Niamey to Benin's Cotonou port would have taken around three days, whereas travelling to N'Djamena takes "four or five days, if everything goes well at the borders," the logistics specialist told AFP.

From Chad's capital, there are a further 2,000 kilometres of "poor roads" before reaching Douala, requiring "the best part of a week" and an escort to cover, they added.

Some of the equipment may simply have to be left in Niger rather than paying the cost of an expensive repatriation.