While France's political class rallied together after attacks in November 2015 that killed 130 people in Paris and on the Charlie Hebdo magazine and a Jewish supermarket in January 2015, criticism of the Socialist government began hours after yesterday's carnage in the French Riviera city.
"I am not an investigator. (But) if all measures had been taken, the tragedy last night would not have happened," Juppe, a former right-wing prime minister, told RTL radio.
A French parliamentary inquiry last week criticised numerous failings by the intelligence services over both sets of terror attacks in Paris last year.
Yesterday, witnesses said a truck drove at speed for two kilometres through people watching a fireworks display on France's national day in Nice.
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"We know of course that there are still flaws and shortcomings. The parliamentary inquiry after the November attacks showed that," he said, referring to the report criticising France's response to the attacks.
Juppe, who is a leading contendor to be the right's candidate for the presidency in 2017, also called for a thorough probe into the attack.
"We must first shed light on the circumstances of this tragedy to the extent possible. I am not seeking to blame anyone at this stage naturally," he said.