PARIS — For the second time this year, France has found itself singled out for calculated terrorist attacks that have at once stunned and united the country. But perhaps no one was singled out by Friday’s carnage more than the nation’s leader, President François Hollande.

Mr. Hollande was in the soccer stadium that was the attackers’ most spectacular target — a thwarted attempt by suicide bombers to blow themselves up under his very nose.

His name was evoked by the attackers who stormed a rock concert elsewhere in Paris, declaring, according to a witness, that their carnage “was the fault of Hollande. This was the fault of your president. He didn’t have to intervene in Syria.”

It was a strike not only at France but also at his policies, presidency and leadership, at home and abroad.

That messy reality presents Mr. Hollande with a particularly stark quandary: Taking the fight even more aggressively to Syria and Iraq, as he pledged to do on Saturday, carries the risk of inviting still more attacks from the Islamic State and its sympathizers and of fanning simmering divisions between Muslims and non-Muslims in France.