"Hotspot ahead!"The curt message comes over the radio, warning troops aboard the eight-vehicle UN peacekeeping convoy to check their weapons one more time and go on maximum alert.A grim sight greets the Germans as their armoured contingent approaches the village of Doro in the savannah south of Mali's broiling desert: a line of burned-out fuel tankers, pickup trucks and military vehicles.They have been destroyed by homemade bombs and armed raiders - a reminder of the jihadist threat that hangs over northern Mali like a leaden pall.The scorched, dusty north has been in the grip of an Islamist uprising since 2012. The following year, intervention by French troops drove the jihadists out of key northern towns, but the insurgency was displaced rather than crushed. Conflict spread to the centre of the vast Sahel state and spilled into Burkina Faso. But jihadism is just one factor in a mosaic of violence that includes ethnic clashes and gangster activity.The RN15 - the highway that leads from Gao, the main town in the north, and reaches down into Mopti, in the centre - has seen dozens of attacks over the past three years.A map used by the German paratroopers in the UN operation MINUSMA is studded with markers of attacks since 2016 between Gao and Doro: "IED", or improvised explosive devices, "holdups," "armed attacks" and "complex attacks", or combined operations."This part is called the 'Highway of Death'," a UN official said, speaking on condition of anonymity."Recently, there have been lots of bus holdups," the official added. "The bandits rob all the passengers - they even order people to transfer them money with their mobile phones."Such incidents led road transporters to use the highway only in convoys on a dangerous stretch of 150km, but that is still not sufficiently safe and UN forces decided to patrol, looking for IEDs."Today we want to collect data for the roadbook, because we have to know what are the vulnerable points of the road," German Lieutenant-Colonel Mickael Weckbach told AFP.The convoy rolled cautiously into Doro, where the main street doubles as the local market and sidestreets are a de-facto parking lot for camels. The village of mud huts also has a detachment of the Malian army.Peasant farmers, stock breeders, traders and children mill around in a crush of buses and lorries, while the heavily-armed UN vehicles weave their way through. 'Soldier or militiaman?' As the convoy pulls out, highway watchfulness returns.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook. "We're approaching a place where there have already been four attacks," a slightly nervous observer warns on the radio."A motorbike's coming with an AK," adds a soldier riding atop one of the armoured personnel carriers, referring to an AK47 assault rifle. But the two men on the bike, one wearing battledress, rode past the UN troops with a thumb's-up."Was that a Malian soldier or a militiamen?" asks a sergeant manning a 12.7 mm machine gun.The German UN convoy reaches the scene of the four past ambushes, but troops on the site order all the vehicles to back off while ordnance experts inspect a small bridge next to the crater left by a bomb blast. Half an hour later, the specialists declare the route clear and the convoy moves on.With the spread of unrest from the north of the country to central regions, an average of three explosive devices goes off each day in Mali, according to MINUSMA.Finally, after 14 hours on the road, the German soldiers have found nothing abnormal, but they have gathered a quantity of data for analysis. The main threat during the mission came from the heat, which killed the engine of one of the vehicles. It had to be towed back to base."To be honest, we didn't expect to find IEDs. But it's also important to show our strength," Weckbach said, summing up the patrol.