The eight men involved in the terror attacks last night in Paris have not yet been identified, but tentative reports say that they were a mix of nationalities, with at least one of them being French.

President Francois Hollande hinted at his suspicions about a domestic connection in a speech Saturday. “This is an act of war that was prepared, organized, and planned from the outside, with complicity from the inside that the investigation will establish,” he said.

The country, Hollande said, “will do everything within its power and within the law, on every terrain, domestically and abroad, with our allies who are themselves targeted by this terrorist threat.”

France, more so than any other country in Europe, has been struggling with radicalization within its borders. It’s estimated that France has sent more fighters to Syria and Iraq than any other European country, as these figures from the International Centre for the Study of Radicalisation and Political Violence show.

The Centre estimated in January that about 1,200 of the foreign fighters in Syria and Iraq had come from France, based on news reports and official statistics. In April, the French government put the number of French jihadi fighters closer to 1,430. Another 3,000 people in France were being monitored for their connections to Syria, French senator Jean-Pierre Sueur told the press at the time.

According to these figures, France is responsible for sending between a third to half of all the radicalized fighters from Europe that have made their way to the war zones in the Middle East. Some of them — perhaps 200, according to AFP earlier this year — have returned to France where there are fears they will help organize domestic attacks.

It has become a priority of the French government to stop the flow of fighters. “France will take all measures to dissuade, prevent and punish those who are tempted to fight where they have no reason to be,” Hollande said last year. To that end, the government has launched anti-extremism campaigns to reach out to disaffected youth. After the Charlie Hebdo attack in January, the prime minister announced a $480 million effort to build communities, police hate of all kinds, and fight radicalization online and in prisons.

For instance, the government this year has released a series of anti-radicalization videos on social media, where young jihadi fighters are often recruited.  

“They say, ‘Join us to help the children of Syria,’” one video tells viewers. “In reality, you will be complicit in civilian massacres.”

Another campaign launched last month features interviews with the family members of people who left France to fight in Syria or Iraq. “She was looking for a better world, but I think she found hell.” says Baptiste, whose daughter ran away when she was 17, according to the video. “They stole our child.”