BEIRUT (AP) — The Islamic State group is often described as the most fearsome jihadi outfit of all: a global menace outweighing al-Qaida, with armies trembling before its advance.

But while the group has been successful at seizing parts of Iraq and Syria, it is no unstoppable juggernaut. Lacking the major weaponry of an established military, it wields outsize influence through the fanaticism of a hard core of several thousand, capitalizing on divisions among its rivals, and disseminating terrifying videos on social media.