Jihadists are scoring gains in the Sahel, defying efforts by five countries in the fragile region to fight back with Western help against Islamist militancy.
Areas of insecurity on the Sahara's poor, arid southern rim are widening, analysts say, even as the so-called G5 Sahel group -- Burkina Faso, Chad, Mali, Mauritania and Niger -- seek to expand their anti-terror campaign.
"Overall, the security situation in the Sahel continued to deteriorate, having spillover effects on neighbouring countries that are not members of G5 Sahel, including Benin, Cote dâ€™Ivoire (Ivory Coast) and Togo," United Nations Secretary-General Antonio Guterres said this month.
Guterres said in recent months, armed groups had been sighted on Mauritania's border with Mali, attacks on security forces had continued unabated in Mali itself, "terrorist groups, militias and armed gangs" had proliferated in Burkina, and jihadists had killed dozens of soldiers and civilians in Niger.
At the end of last year more than 120,000 people had been displaced in Mali, a tripling in the space of a year, while 160,000 have fled their homes in Burkina.
According to a French military source, there are about 2,000 fighters across the Sahel, of which up to 1,400 are in Mali.
Their hallmark tactics -- brutal gun attacks, roadside bombings and hostage taking -- seek to weaken the rule of law and authority of the state, often fomenting intercommunal fighting on which they capitalise.
"There are not necessarily more attacks, but the attacks are more violent. The groups have acquired some technical competence," said Mahamadou Sawadogo, a researcher at the Crossroads of Study and Research for Democracy and Development at Senegal's Gaston Berger University.
"There's an increase in power at the quantitative level and also in their efficiency," noted Lassina Diarra, author of a book on West African countries facing transnational terrorism.
"In Burkina, there appears to have been a merger of means between groups affiliated to Al-Qaeda and those affiliated to the Islamic State," he said.
"It seems that they now lend each other a helping hand."
Diarra suggested that battle-hardened fighters may have arrived from the Middle East after the so-called Islamic State lost its territory in Syria.
"We are seeing changes in operational methods with the use of explosives, mines and car bombs" combined with more ambitious raids, he said.
Both academics showed concern at the weakness of regional armies, particularly in Burkina.
The problems facing the G5's armed forces are well known. Their militaries are under-equipped and poorly trained, even though governments are already earmarking as much as 15 percent of their budgets on security.
With support from France and others, the G5 countries are pushing ahead with plans for a pooled 5,000-man force.
But at present, they lack coordination in border zones, where jihadist forces are particularly active and whole populations become internally displaced.
"The armed groups play with these borders," Sawadogo said.
Even if jihadists do not maintain a permanent presence, their zone of influence is growing.
"They don't need to be there all the time, holding ground. They create the feeling of insecurity with sporadic attacks," Diarra said.
"They harass the symbols of the state" and drive out civil servants working for it, Sawadogo noted. "They don't have a hold over areas but they are not seeking to be a static force. It's governance from a distance."
"They have created comfort zones," he argued. "And now there's a corridor" that extends from southwest Burkina Faso to Mali and western Niger.
Hearts and minds?
"We need to fight against the ideology of the jihadists," Diarra said when asked how to fight back. He recommended providing instruction for imams that would avoid radical preaching and "factors for recruitment".
"We have to fight on the same ground as the jihadists, use the same strategy," Sawadogo said.
"For now, the jihadists benefit from complicity. They move around, prepare attacks and routes to fall back. They pass through villages."
But while village folk know about the armed groups, the security forces get little or no intelligence to strike, he said.
Both researchers insisted on the need to uphold the presence of the state, with officials in place and a degree of local investment to help restore confidence among citizens.
With the right structure in place, they said, people might be inclined to help the security forces and ignore jihadist extremism.