The dominant view of the US-led coalition against the Islamic State (ISIS), Operation Inherent Resolve, is that its fundamental goal is the defeat of ISIS.
And so, in the wake of the routing of ISIS from Iraq and Syria, the core justification for an ongoing US military presence in Syria is ensuring that no post-mortem ISIS insurgency arises.
That the US is unequivocally opposed to ISIS is simply taken for granted.
Yet a closer look at the history of US involvement shows that counterterrorism has been a lesser concern relative to geopolitical and strategic goals. Whenever the goals of expanding territorial control or weakening rivals conflicts with the goal of opposing ISIS, the entity was either ignored or even empowered in pursuit of these more paramount concerns.