London Mayor Sadiq Khan has announced he will be "reviewing" the city's safety measures following the terrorist attack that killed more than 80 people in Nice.
He declared that the capital would "stand united" with France and insisted the "poisonous and twisted" terrorists would be defeated.
Speaking on a visit to Gatwick Airport, Khan said: "I will reassure all Londoners that today we will be reviewing our own safety measures in light of this attack and that I and the Metropolitan Police Commissioner will do everything possible to keep Londoners safe."
He offered his "deepest sympathies" to the people of Nice, describing the attack as "a horrific and unspeakable act of terror on a day of celebration".
He said the French people "have suffered so much pain in recent times".
"Londoners today stand united with Nice and all of France in our grief. We're also united in our determination to root out and defeat the sick and evil individuals who have tried to divide us with this cowardly act of terror.
"They will not win. Not in France, not in London, not anywhere. We will defeat their poisonous and twisted ideology."
The Government today issued advice on Thursday night and Friday morning, urging people travelling to France to follow the safety instructions of French authorities.