"We noticed excitement from the moment that young French radical Muslims learned that Shariah law was being applied in north Mali," he said. Many French radicals with dual citizenship — French-Malian, French-Nigerien, French-Nigerian, French-Congolese — wanted to go.
About 15 people have traveled to the region, and a few have returned to France, Trevidic said. Legal cases have been opened involving about 10 people — most of whom never left France but sent allies to Mali to join Islamic groups.
A challenge for French authorities is monitoring them to see if they plot attacks and not arresting them right away — to solidify judicial cases against them — and especially trying to "control" those who do return home to France.
The French military intervention that started Jan. 11 all but halted militants' departures toward Mali, Trevidic said. "For now, the situation is too tumultuous," he said. "We're in a bit of wait-and-see about what happens in the months to come."
Since the French air and ground campaign began, militants in France have lowered their profiles.
"Everybody ... has ducked. They're not getting noticed. A big problem in the current legal cases is when people in groups being monitored converse and have normal relations, and then suddenly cut all ties. They don't call each other, they stop seeing each other," Trevidic said.
"You think, 'it's because of the military action, it's hot, and they don't want to get noticed'," he added. "But it can also be worrisome, sometimes, it could be a sign that they are getting close to an action."
"Maybe it will calm down, by some miracle. But it's all going to depend on the states involved and how they manage their own problems," he said. "If the French army leaves, will the Malian military be strong enough to thwart the counterattacks of the Islamists? For the moment, we don't quite have that impression."