France on Sunday rose its security alert to its highest level after a recent deadly attack at a concert hall on the outskirts of Russia's capital, Moscow.
The attack was claimed by the Afghanistan-based "Islamic State Khorasan Province" (IS-K) group.
Over 137 people were killed and 140 injured in the attack on the Crocus City Hall on Friday. Authorities have remanded four suspects, identified in Russian news reports as citizens of Tajikistan, in custody pending trial.
What did the French government say about the terror alert?
Prime Minister Gabriel Attal announced the measure in a post on the platform X, formerly Twitter.
"We have decided to raise the Vigipirate state to its highest level: attack emergency," he said, referring to France's security alert system.
Attal said that the government had made the decision "taking into account the Islamic State's claim of responsibility for the attack [in Moscow] and the threats that weigh on our country."
France's alert system has three levels. The "attack emergency" level is activated in the wake of an attack in France or abroad or when the threat of an attack is considered imminent.
The highest alert allows for exceptional security measures, included increased patrols by armed forces in public places.
France was already on high alert ahead of the Paris Olympics and Paralympics this year.
The prime minister's announcement came after President Emmanuel Macron held an emergency security meeting following the Friday attack.
What do we know about IS and its Khorasan branch?
IS-K is one of the most lethal branches of the "Islamic State" (IS) terror group, having killed thousands in Afghanistan and Pakistan since 2015. While it has largely been active in Central and South Asia, it has also pursued operations targeting Europe and North America.
The Khorasan group swore alliegance to IS in 2015, when IS controlled wide swaths of Iraq and Syria.
In December, German police arrested a citizen of Tajikistan who was suspected of planning an attack on a historic cathedral in Cologne on New Year's Day. Authorities accused him of being a ringleader in an IS-K terror cell.
IS has carried out multiple attacks in France, including the attack on the Bataclan theater and other sites in Paris in 2015.
In connection with Friday's attack in the Russian capital, Moscow's Basmanny District Court formally charged four suspects between the ages of 19 and 32 with committing a deadly group terrorist act. They face a maximum sentence of life imprisonment. Two of the defendants had pleaded guilty, the court said.