Even as US officials tout successes in Iraq and Syria, they warn that many Islamic State terrorists have gone underground and are biding their time, particularly as the Trump administration weighs troop drawdowns in the Middle East. “The physical caliphate offered IS advantages in operational terms as well as in projecting itself. An Islamic State that “is far more decentralised, and potentially far more a franchise with greater opportunity, is likely to prove more difficult to combat,” according to James Dorsey, a senior fellow at RSIS.