The United States is at risk of getting sucked into another misadventure in Iraq, three years after President Barack Obama ended what he called a dumb war. That entanglement of dubious justification left Iraq - the fabled Mesopotamia of antiquity - in a shambles for the net gain of one dictator's removal. (Of course, America also coveted the oil.) The US-led invasion hurt America's moral standing, which the nation should guard above all of its other leadership attributes.

Mr Obama has consistently argued that there is no American military solution to Iraq's existential dilemma spawned by conflicting regional allegiances based on ethnicity and faith. These have bubbled up and consumed the country in sectarian violence as a consequence of the previous American attack begun in 2003. Just last week, when ordering air strikes to evacuate persecuted minorities fleeing the murderous Islamic State in Iraq and Syria (ISIS) militants, Mr Obama said he would not allow the US to be dragged into another war in Iraq.

But military operations unfolding in the past 48 hours show he is being pulled along by the dynamic of war. He seems to have little choice, given the threat of ISIS militants establishing a firmer hold on the ground. US bombers and fighter jets have been helping local fighters to regain control of a strategic dam in Mosul. ISIS has captured dams elsewhere in Iraq, a tactical gain of lethal proportions. Wresting back these assets will go well beyond the remit of humanitarian assistance the President initially imposed on his mission. In Baghdad, the central government, which controls only about half of the country after losing territory to the ISIS advance, is pressing the US to widen its air attacks on ISIS positions, including around the region of the capital.

Pressure also is growing from Mr Obama's Atlantic allies, principally Britain, to extend the scope of intervention to counter the ideological virulence that ISIS represents. This is much like a reprise of Afghanistan and the Taleban. Yet, if the Americans end up fighting the Iraqi government's war to evict the extremists and shut down their caliphate, it will be war all over again as no such campaign is possible without the use of troops.

Then it gets complicated. Hitting ISIS in Iraq cannot be segregated from its role in the Syrian war, where ISIS is on the "right" side of the US-backed campaign against the Assad forces. And supplying arms to the Kurdish resistance in Iraq to take on ISIS will inflame Turkey, which is fighting its own Kurdish insurgency. This is one big mess. Mr Obama wanted to do good and avoid doing stupid things, but he - and the world - seem to have very few good options.