The truck attack on Bastille Day crowds in Nice is likely to have a huge impact on French politics, a terrorism expert says.
Dr Greg Barton is head of the Counter-Terrorism Centre at Deakin University in Melbourne.
He told Afternoons if the perpetrators were revealed as Islamic State (IS), right-wing parties in France would use that as an opportunity to attack the government over its immigration policy.
"It's an assault on the heart of modern Frenchness, in a way that will really resonate," he said.
"Being in Nice in the south of France, right-wing politicians like Marie Le Pen have done well from a reactionary sentiment and people responding with anxiety - and I think this happening on Bastille Day will really emphasise that."
The right-wing National Front led by firebrand politician Marine Le Pen held street rallies in the south of France following the Paris attacks.
The party has said that if it had been in power, the attack on the Bataclan night club would never have happened.
Dr Barton said France had become a target for terrorism directly because thousands of young French men had gone to fight in Syria and Iraq, and many hundreds had since returned with specific instructions to plan terrorist attacks of the kind seen today.
"They are in numbers too large for the police to track effectively," he said.
"And it's a numbers thing really, nothing to do with France specifically"
French President Francois Hollande said the attack on Nice was clearly a terrorist assault and that the state of emergency imposed since a previous attack on Paris last November would now be extended for another three months.
"They can't give the public false promises on security they can't deliver on," Dr Barton said. "On the other hand they can't keep the state of emergency in place indefinitely."
"French Muslims find it hard to get work, they feel alienated; and while only a tiny fraction are drawn to terrorism, it's easier to draw those people when they're feeling like that." Dr Barton said.
And while the attack may again fire up the arguments over open borders in Europe, Dr Barton suggested the French government trod carefully.
"Islamic state may prey on immigrant communities, but it's the second-generation that becomes involved, it's not people who have just recently arrived, it's their children or sometimes their grandchildren," he said.
"It might be tempting to think its the new migrants and the open borders policy to blame here, but it's not."