The problem appears to be the gap between surveillance of members of the criminal-terrorist extremist nexus, and prosecuting perpetrators for crimes such as acquiring illegal firearms.
In the 55-minute statement, Baghdadi congratulated what he described as the "striking lions" behind recent attacks in Canada and Europe and called on followers to continue carrying out attacks.
The Chechen-born French citizen was on two terrorism watch lists.
Several leaders and organizations offered condemnatory words and statements of support for the victims of Friday's attack.
"Islamist radicalization is a threat to our society, and not just when it leads to violence. It's a challenge every time the law of the state is respected only if compatible with religious tenets."
The French singer's social media claimed that the French state, not jihadists, were respinsible for terrorism.
Diab has denied any connection to the 1980 bombing of the synagogue on Copernic Street, which killed four people.
During a three-day killing spree in January 2015, gunmen killed reporters and illustrators at satirical weekly Charlie Hebdo, police officers and shoppers at a Jewish supermarket.
Terrorism is not a new phenomenon for France, but the 2015 attacks became a tipping point.
Abdelkadar Merah is accused of helping his younger brother, Mohammed, kill four Jews and three soldiers in 2012.