When the Islamic State’s Egyptian arm claimed responsibility for blowing up a Russian charter plane over Sinai two weeks ago, some analysts wondered if the group’s so-called Sinai Province of the Islamic State had acted on its own and leapt out in front, even at the cost of risking a Russian military backlash on the parent group in Syria and Iraq.

But the attacks last week in Paris and Beirut, which the Islamic State also said it carried out, appear to have settled that question and convinced even skeptics that the central leadership was calling the shots.

“There is a radical change of perception by the terrorists that they can now act in Paris just as they act in Syria or Baghdad,” said Mathieu Guidère, a terrorism specialist at the University of Toulouse. “With this action, a psychological barrier has been broken.”…

“Their goal is an unconventional urban guerrilla war,” said Franck Chaix, an officer of the Gendarmerie, France’s semi-military police force, and a former head of its special intervention force, G.I.G.N.