The Russian province of Dagestan, a flashpoint for Islamic violence in the North Caucasus, is feeding hundreds of fighters to the Islamic State in Syria — and now some are coming back home with experience gained from the battlefield.

The departures mean that the region itself has become markedly less violent recently with fewer bombings and shootings. And the returning fighters have either landed in jail or been kept under close police surveillance. But there are long-term concerns that the presence of radical Muslims trained in IS warfare could lead to greater instability and violence.

“We can’t allow them to use the experience they have just gained in Syria back home,” Russian President Vladimir Putin said recently.

Eduard Urazayev, a former minister in Dagestan’s provincial government, and now a political analyst, said that poverty and unemployment in the region made the IS recruiters’ job easier. “If the high level of corruption and unfavorable socio-economic situation remain,” Urazayev said, “it may further fuel protest sentiments and increase sympathy for the IS.”

The Islamist insurgency that has swept Russia’s North Caucasus after two separatist wars in Chechnya has a proclaimed goal of carving out an independent state governed by Shariah law. The Caucasus Emirate, an umbrella group comprised of rebels in several Caucasus provinces, has sworn allegiance to the IS.

Alexei Malashenko, an expert on Islam with the Carnegie Endowment’s Moscow office, said that officials in the Caucasus had an interest in encouraging the militants to move out of the region.

“A drop in the Islamists’ activity and the reduction in the number of casualties in the North Caucasus in 2014-2015 were the result of militants leaving for the Middle East,” Malashenko wrote in a recent article.

Officials said they were keeping close watch on those who return. Dagestan authorities have tried to register all followers of Salafism, a radical branch of Sunni Islam, taking their fingerprints and DNA samples.

Sharaputdin Arslanbekov, a police official in Makhachkala in charge of fighting extremism, said the official number of Dagestan residents who have left for Syria stands at 419, but reliable intelligence indicates that the actual figure is around 700, a significant share of an estimated 2,500 Russian citizens with IS.

Arslanbekov said IS recruiters were working actively in universities and schools, taking advantage of economic and social problems in the region. “The recruiters are quite sly and well-prepared, they know methods of ideological indoctrination and are good psychologists,” he said.

Police captured five former IS members and killed three others, he said, adding that nine of those who fought alongside the IS in Syria have voluntarily surrendered after coming back home.

Gazimagomed Aligadzhiyev, a native of the mountainous village of Gimry, a key center of Salafism in Dagestan, was one of those who left for Syria and spent three months at an Islamic State training camp in Syria before he decided to come back. Upon return, he joined a local militant group but eventually got sick of hiding and turned himself in to the authorities.

“We only went out at night, as they could spot us in daytime. I haven’t seen sunlight since December,” he told Russian state television.

Even though some officials in the Caucasus may feel relief about militants fleeing to Syria, the Kremlin has voiced strong concern about the potential threat the militants could pose upon return.

Putin has described the IS threat to Russia as a key factor behind his decision to launch air strikes on militants in Syria. He said that between 5,000 and 7,000 people from Russia and other former Soviet countries are now fighting alongside Islamic State militants.

Meanwhile, Russia’s air campaign in Syria has drawn threats of retaliation from militants there, raising the danger of IS-driven terror in a country that has seen numerous suicide bombings and other extremist attacks in the past.

They included the 2002 hostage-taking raid on a theater in Moscow, which left 130 hostages and all 40 attackers dead, and the 2004 seizure of a school in Beslan in southern Russia, in which more than 330 people were killed and over 800 others were wounded. In 2010, twin suicide bombings on the Moscow subway killed 40 people and wounded over 120, and a 2011 suicide bombing at a Moscow airport killed 37 and injured more than 180.

Alexander Bortnikov, the head of Russia’s Federal Security Service (FSB), the main KGB successor agency, said recently that under the brunt of Russian airstrikes, some militants were trying to leave the warzone in Syria with a goal to conduct terror attacks in Russia, Europe and elsewhere.

A few weeks ago, the FSB arrested a group of people, including some trained by IS in Syria, who were accused of plotting a terror attack on Moscow’s public transport system. It also found a home-made bomb loaded with five kilograms of explosives.

IS has been active on social networks across Russia and other ex-Soviet nations in search of new recruits, focusing primarily on young people.

People from Kyrgyzstan and other ex-Soviet Central Asian nations, where the majority of the population is Muslim, have been a top target for IS recruiters. Poverty and lack of jobs have pushed many to go to Russia to work as migrant laborers, and Russia’s economic downturn helped make the IS recruitment effort easier.

One such recruit, Babur Israilov, a 21-year old citizen of Kyrgyzstan, went viral on the Internet last month: A video showed him weeping while climbing into a vehicle rigged with explosives, just minutes before blowing himself up in a suicide mission in Syria.

Those who knew Israilov said he had gone to Russia in search of a job, and apparently was lured into joining the IS there. Kyrgyz officials wouldn’t comment on the case pending a probe.

Along with the poor and the desperate, IS nets have caught some members of the middle-class. A second-year student of the elite Moscow State University, who studied Arabic and developed an interest in Islam, left to join the IS but was detained on Turkey’s border with Syria a few days later after her father raised the alarm.

Most local imams in Dagestan shun radical views, but they have found it hard to counter the appeal of radical ideas promoted by the Islamic State. Some imams who spoke against radical Islam have been killed.

Muhammad-Haji, an imam in Makhachkala, who spoke on condition of anonymity because he feared Islamist revenge, said many young people fell under the spell of the extremist ideas and he found it hard to persuade them to change their views.

Tanya Lokshina, the Russia program director at Human Rights Watch, said that police abuses fueled anger against the authorities, contributing to the popularity of IS among young people in the region.

Unlike Dagestan, which has remained the epicenter of the Islamic insurgency in recent years, Chechnya has become more stable under the leadership of Moscow-backed strongman Ramzan Kadyrov, who has incorporated many former rebels into his feared security forces. International rights groups have accused him of using extrajudicial killings, abductions and torture to uproot the Islamist insurgency in the region.

Kadyrov claims that “tens of thousands” Chechens were eager to travel to Syria to help President Bashar Assad’s military.

“By helping Syria,” Kadyrov said, “we are protecting our country.”

(AP)