The terrorist threat posed by Islamic State morphed from an uncertain menace confined largely to the Middle East into one of the biggest global security challenges since the end of the Cold War.
For the first time the militant group launched major terror attacks from its strongholds against distant targets, including the deadliest-ever on French soil. A couple killed 14 people in San Bernardino, Calif., in the worst attack in the U.S. since Sept. 11, 2001; the wife had pledged allegiance to Islamic State.
Islamic State consistently urged sympathizers to strike the West, but until recently the group devoted its energy to seizing territory in Syria and Iraq for a so-called caliphate to be ruled according to its puritanical version of Islam.
“It was clear the group was calling for attacks,” said Raffaello Pantucci, a counterterrorism expert at the Royal United Services Institute, a think tank in London. “But it wasn’t clear there was anything strategic to it. It was more about throwing sand in our eyes.”
That changed with a string of lethal attacks directed at some of the group’s main enemies, including Turkey, Hezbollah and possibly Russia as well as the West.