– The father says he did not raise his son as a Muslim — and he regrets his decision now.

Maybe if Reda Nidalha, born and bred in the historic Dutch university city of Leiden, had learned about moderate Islam, it would have been harder for extremists to "brainwash" him and help him travel to Syria, his father said.

Mohamed Nidalha sent his son to Belgium to stay with his uncle after Reda fell in with a bad set of friends in Leiden.

But Reda soon came into online contact with a Belgian in Syria who linked him up with a notorious terror recruiting network, Sharia4Belgium.

The 20-year-old who grew up liking girls and going to discos suddenly changed, thanks to a toxic cocktail of online propaganda and covert contact with extremists in Belgium, one of Europe's hot spots for Islamic radicals.

"He went to the mosque, grew a beard and went to readings somewhere in a secret place — not in a mosque, but in a house somewhere," says Nidalha, a 49-year-old immigrant from Morocco. "There, he was brainwashed, and prepared. Inside two months he was made totally crazy."

Reda is emblematic for hundreds of disaffected Muslim youngsters from the largely secular countries of Belgium and the Netherlands who have turned their backs on their liberal Western societies and been sucked into the sectarian maelstrom of Syria's civil war. A Dutch intelligence agency estimates around 180 Dutch citizens left the country to fight in 2014 alone.

Nidalha is at a loss to explain why exactly his son turned to violent extremism while trying to make a fresh start in Belgium.

But he suspects the jihadi recruiters saw in his son an easy mark — a kid from a broken home struggling with life and looking for a new direction.

"They pick on the easiest prey they can easily brainwash," Nidalha said.

Reda has been gone for almost a year now. Nidalha is certain he won't see his boy alive again, but worries what he would be like if he did return.

"Imagine my son comes back. What kind of son do I get back? I don't get the same son as before," he said. "Because my son has now learned things there in Syria. My son might be able to make bombs now, maybe he can shoot."

Mike Corder