The Islamic State of Iraq and Syria must be destroyed at all costs, France's defence minister said Sunday, as investigators worked to identify the third militant killed in the strike on the country's national stadium during the Nov. 13 Paris attacks.

"We must annihilate Islamic State worldwide... and we must destroy Islamic State on its own territory," Defence Minister Jean-Yves Le Drian told French media.

"That's the only possible direction," he said, adding that any country "who wants to participate militarily is welcome."

Meanwhile, police in France posted a photo of the third attacker who was killed in the assault at France's national stadium on Nov. 13, the day of the Paris carnage. They posted the photo on Twitter, appealing to the public for information that would help identify him.

[<a href="https://twitter.com/hashtag/Appel%C3%A0T%C3%A9moins?src=hash">#AppelàTémoins</a>] La <a href="https://twitter.com/hashtag/PJ?src=hash">#PJ</a> cherche à identifier le 3ème auteur d'un des attentats du 13/11 <a href="https://twitter.com/hashtag/StadeDeFrance?src=hash">#StadeDeFrance</a> <a href="https://twitter.com/hashtag/ParisAttacks?src=hash">#ParisAttacks</a> <a href="https://t.co/TZxieSUlyY">pic.twitter.com/TZxieSUlyY</a> —@PNationale

ISIS militants have claimed responsibility for attacking the stadium just north of Paris, as well as a concert hall, cafés, and restaurants, killing 130 people and wounding hundreds.

Since then, France has intensified its aerial bombing in Syria.

Tensions high, rhetoric intensifies

As well, Western leaders stepped up the rhetoric against the Islamic State group, which has also claimed responsibility for the Nov. 12 suicide bombings in Beirut that killed 43 people and injured more than 200, and the Oct. 31 downing in Egypt's Sinai Peninsula of a Russian airliner carrying 224 people.

Tensions have been high in Europe since the attacks in Paris. In Belgium, the manhunt continued Sunday for suspected militant Salah Abdeslam, 26, who slipped back home to Brussels from Paris shortly after the attacks.

Two of the Paris suicide bombers, Salah's brother Brahim Abdeslam and Bilal Hadfi, had been living in Belgium.

Belgian Interior Minister Jan Jambon on Sunday said "several suspects" tied to the Paris attacks could be at large in the country.

In a sign of the nervousness that has swept through Paris, some travelers at the Gare Du Nord train station ran out of their trains on Sunday after hearing noises they thought were gunshots but were actually caused by a pigeon being electrocuted on the tracks.

A state of emergency in France –­ which allows police raids, searches and house arrest without permission from a judge – has been extended for three months. As well, a ban on demonstrations and other gatherings has been extended through Nov. 30, when a UN climate conference is scheduled to start with more than 100 heads of state attending, including Canadian Prime Minister Justin Trudeau.

Hollande, Cameron to meet

President François Hollande is to meet in Paris with British Prime Minister David Cameron on Monday, then go to Washington and Moscow later in the week to push for a stronger international coalition against ISIS.

Le Drian said the French aircraft carrier Charles de Gaulle, sent to help operations against Islamic State militants in Syria, will be "operational" from Monday and "ready to act."

In Kuala Lumpur, U.S. President Barack Obama said the world would not accept the extremists' attacks on civilians as the "new normal." As well, Obama vowed the United States and its international partners would not relent in the fight against the Islamic militants.