America’s regional partners decried the rise of Iranian influence as the United States stepped back, and feared Maliki’s steps against Sunni politicians could reignite civil violence, but the White House brushed off their concerns in both Iraq and Syria. And so the Gulf states sent their own support to Sunni tribes in western Iraq and militias battling Assad in Syria, stoking the sectarian flames and setting the stage for extremists to outbid them. As ISIS began to gain ground among Sunni populations alienated from the central government, the administration didn’t see any reason to invest in persuading Maliki toward a political accommodation that might have tamped down the emergent Iraqi Sunni militias and held Iraq together. That’s not to say Obama would have succeeded—but because he wanted to turn the page on the Iraq experience, he failed to try.

Likewise, Obama’s read of the Syrian conflict as holding only narrow implications for American interests was a signal failure to learn the lessons of the 1990s and recognize the risk that Syria’s civil war could spill over in ways that directly implicated U.S. interests. It did not, in 2012 and 2013, require special foresight to apply to the Syrian case other lessons from history than those Obama focused on. The experience of the 1990s clearly suggested how a neglected civil war offered easy opportunities for a violent jihadist movement—just as the Afghanistan war did for the Taliban in the mid-1990s—and how large-scale refugee flows would destabilize Syria’s neighbors, including key U.S. security partners like Jordan and Turkey. And as we now know, ISIS used the security and governance vacuums created by the Syrian Civil War to consolidate a territorial and financial base that the United States has been seeking since late 2014, with limited success, to undermine.

These two errors of understanding and judgment, both driven by the president’s commitment to avoid his predecessor’s mistakes, left major risks to regional stability unaddressed, and thus fed the rise of an ISIS threat so significant as to compel Obama, in August 2014, to overturn his longstanding preferences and recommit American blood and treasure to fighting Islamist extremists on the ground in Iraq, and now in Syria. His errors (as well as the famous “red line” climbdown) also provoked anxious regional partners to take their own initiatives to advance interests they felt Obama had slighted—condoning jihadism at times along the way, and very often exacerbating the disorder and sectarianism on which ISIS feeds.

Obama feared a slippery slope going up against Bashar al-Assad in Syria—but the war against ISIS is the slipperiest slope of them all. In just under two years, the administration has moved from airstrikes, to 475 additional military advisers in Iraq, to over 4,000 troops on the ground including U.S. special-operations forces in both Iraq and Syria. At the same time, the metastasizing threat from ISIS is forcing Obama to order limited military strikes in Libya, consider plans for further military intervention there, and build up military commitments to the Sunni Arab states of the Persian Gulf—the latter two steps, if Goldberg’s piece is accurate, against his own inclinations. An American president who, in May 2013, rejected the notion of a “global war on terror” has now launched one.