Samer recalls the gruesome shock of seeing his friend’s headless corpse strung up above Raqqa’s main square.

When the Islamic State raised its black flag over the Syrian city of Raqqa in early 2014, it began its transformation from fringe regional player to fearsome global threat. By the end of that year, it had seized large stretches of territory in Iraq and Syria, creating a rogue state …

Just two weeks after President Donald Trump triumphantly declared the “100 percent” defeat of ISIS’s caliphate, his national security advisor, John Bolton, admitted on television that “the ISIS threat will remain” and that this explained why a small “observer force” would now stay in Syria.