In a statement via its Amaq news service, IS said one of its “soldiers” carried out Thursday night’s attack “in response to calls to target nations of coalition states that are fighting (IS)”.
Tunisian Mohamed Lahouaiej-Bouhlel, 31, ploughed a 19-tonne truck into a crowd of people who had been watching Bastille Day fireworks in the French Riviera city, killing 84 and injuring 200.
After crisis talks in Paris, French Defence Minister Jean-Yves Le Drian noted that IS had recently repeated calls for supporters to “directly attack the French, Americans, wherever they are and by whatever means”.
“Even when Daesh is not the organiser, Daesh breathes life into the terrorist spirit that we are fighting,” he said, using an Arabic name for IS.
Facing its third major terror attack within 18 months, the French government is coming under fire from opposition politicians and newspapers demanding more than “the same old solemn declarations”.
Interior Minister Bernard Cazeneuve said that, after gunmen and suicide bombings, France was now facing “a new kind of attack”.
Speaking as France began three days of mourning yesterday, he said Lahouaiej-Bouhlel “had not been known to the intelligence services because he did not stand out ... by being linked with radical Islamic ideology”.
Marine Le Pen, the far-right leader of the National Front party, called on Cazeneuve to step down.
“In any other country in the world, a minister with a toll as horrendous as Bernard Cazeneuve – 250 dead in 18 months – would have quit,” she said.
Police said yesterday that they had arrested four more people linked to Lahouaiej-Bouhlel, in addition to his estranged wife who was taken into custody on Friday.
Cazeneuve said that the father-of-three “seemed to have been radicalised very quickly, from what his friends and family” have told police.
“We are now confronted with individuals open to IS’s message to engage in extremely violent actions without necessarily having been trained or having the weapons to carry out a mass (casualty) attack,” he said.
At least 10 children were among the dead as well as tourists from the United States, Russia, Ukraine, Switzerland and Germany.
A spokeswoman for the Nice paediatric hospital said 16 bodies had not yet been identified.
She said that five children were still in “critical condition”, and an eight-year-old in a stable condition had not been identified.
Cazeneuve said the carnage had “deeply shocked the French and at the same time shows the extreme difficulty of the anti-terrorism fight”.
The Islamic State also claimed responsibility for the November 13 attacks which killed 130 people in Paris, while gunmen in January 2015 attacks on the Charlie Hebdo weekly and a Jewish supermarket were linked to both IS and Al Qaeda.
A French parliamentary inquiry just last week criticised numerous failings by the intelligence services over the attacks in Paris.
France is also home to hundreds of suspected militants who have flocked to fight alongside the Islamic State.
Cazeneuve has defended the security measures taken for the celebrations of France’s national day.
He said police cars were unable to follow the truck onto the seaside walkway after it had “violently forced through the barriers” and onto the sidewalk.
The truck zigzagged for 2km (1.2 miles) through the crowd before police bullets killed the driver and brought an end to the carnage.
