France was plunged into shock this weekend by the beheading of a Frenchman in Algeria who had been held hostage by terrorists linked to Islamic State.France has participated in the US-led air strikes against Islamic State over the past few days.Hervé Gourdel, a mountaineering guide and photographer from Nice, was taken hostage on September 21, when gunmen stopped his vehicle in remote mountains to the east of the capital, Algiers.On Wednesday, a video showing his beheading was released by the so-called Soldiers of the Caliphate, a splinter group linked to Islamic State. Even if the event itself did not come as a complete surprise after France’s involvement in the war on global terrorism, the footage led to a profound sense of shock in the country.Ahead of his speech on Wednesday at the United Nations General Assembly, President François Hollande confirmed Gourdel’s execution.“Our compatriot has been cruelly murdered in a cowardly assassination,” he told reporters.“Hervé Gourdel was killed because he was French,” he continued, before declaring: “My determination is total and this aggression only strengthens it... France will continue to fight terrorists everywhere.The operation against Islamic State will continue. The military strikes will continue as long as necessary.”The next day’s newspaper headlines read: “France is already at war.” Facing the threats, Interior Minister Bernard Cazeneuve said: “France is not afraid...” But his security services and other authorities could neither deny nor confirm Iraqi Prime Minister Haider al-Abadi’s “credible claims” of planned terrorist attacks on the Paris metro and/or the New York subway.Nevertheless, the ministry, responsible for all police and security services in the country, reinforced security in public places and transportation hubs, while flags were flown at half-mast over public buildings on Sunday.In cities across France on Friday, gatherings were held in memory of all the recently murdered Islamic State hostages and to denounce the barbarity of the jihadists.One of the main demonstrations was held in front of Paris’s Great Mosque, after a call from Dalil Boubakeur, a mufti and rector of the mosque.“We can’t not react, we can’t accept this... as human beings we are overwhelmed,” a Muslim woman told France 2 TV.An Algerian man said: “They are not Muslims, but bandits.”Some lit candles, while others brandished placards reading: “Not in my name,” and “Hervé Gourdel, a victim of Islamist terrorism.”But Jewish historian, journalist and essayist Benoît Rayski was not impressed by the Muslim community’s demonstration of solidarity. “There were only a few hundred in front of the Great Mosque. But where were all the others?” he wrote on the Atlantico website, referring to the tens of thousands who protested against Israel during this summer’s war in Gaza.