The summary moment of Barack Obama’s foreign policy came in August 2013 during a consequential stroll.

Walking on the South Lawn of the White House with his chief of staff, Obama effectively canceled airstrikes against the Syrian regime, which had used chemical weapons on civilians in defiance of an American “red line.” With a deference usually unexpressed on domestic matters, Obama decided to request congressional permission for the use of force — raising a hurdle he seemed reluctant to clear. On the verge of (predictable) congressional defeat, he accepted a face-saving deal, brokered by Russia, which protected the Bashar al-Assad regime in exchange for its surrender of chemical weapons.

My central goal throughout this process has not been to embroil ourselves in a civil war,” argued Obama, adding in a separate interview, “My narrow concern right now is making sure that Assad does not use these chemical weapons again.”

On this foreign policy theory, challenges can be managed by narrowing them. Pick the solvable problem that relates most directly to U.S. interests — in this case, chemical weapons — without becoming embroiled in broader conflicts. And a message was duly sent to friends in the region (the Gulf states, Jordan, the Free Syrian Army): Apart from U.S. humanitarian assistance, they were on their own.

Foreign policy theories seldom get so quickly and thoroughly tested. A narrowed definition of American interests did not actually serve American interests. The death, suffering and chaos of Syria have spilled out across the region, as many predicted. Syria’s civil war fed Sunni militancy, which took advantage of Sunni grievances within Iraq. Lebanon and Jordan are vulnerable to the same sectarian brushfire.

Militant Islamist fighters take part in a military parade along the streets of Syria's northern Raqqa province June 30, 2014. (Stringer/Reuters)

In this case, “somebody else’s civil war” has produced complex layers of global threat. The caliphate that Sunni radicals abortively declared in Iraq in 2005 has reemerged, strengthened by freed prisoners, seized weapons and hard currency. The power struggle between the brutal leader of the Islamic State of Iraq and Syria, Abu Bakr al-Baghdadi, and al-Qaeda’s Ayman al-Zawahiri is not good news. What better way to gain street cred in the global jihadist movement than another attack on the U.S. homeland? U.S. and European officials have compiled a list of thousands of people who might be headed across the Turkish border to join radical groups or returning from the fight. Those holding European passports would have an easier time entering the United States. As usual, the impressive (and sometimes derided) professionals fighting terrorism must be right 100 percent of the time.

After a swift, brutal and profitable terrorist advance, the United States is arguably worse off — more vulnerable, more threatened — than before 9/11. The disorders of the Middle East are not ignorable. They can gather in strength, cross borders, gain new capabilities and ambitions, and threaten our citizens. This only sounds alarmist to those with fading memories of falling towers.

The Obama administration now is engaged in a major course correction: proposing half a billion dollars in aid to the Syrian rebels, sending hundreds of military advisers to help stiffen Iraqi resistance, encouraging the creation of a unity government with greater legitimacy, discouraging Iran and the Gulf states from turning Iraq into another endless proxy war. This is all welcome. It also has some unavoidable implications: Interests can’t be drawn narrowly just to make them appear more manageable. Threats are best opposed before they fully emerge. U.S. leadership is irreplaceable in containing global aggression.

Obama is now likely to face some very difficult choices, even if an Iraqi unity government takes shape. There is little doubt that delay has weakened America’s overall position (and the position of our friends in the region). Even the aggressive counterterrorism tactics conducted in Iraq circa 2007 — think Gen. Stanley A. McChrystal and the Joint Special Operations Command — won’t be able to retake lost territory. A successful effort might more closely resemble the initial stage of the Afghan war in 2001, in which U.S. Special Operations and intelligence forces married up ground-based fighters (the Northern Alliance and Hamid Karzai’s forces), supported by airstrikes.

Pursuing the Iraqi equivalent would require the president to do something he hasn’t done much in an international context. Instead of checking a box — announcing a minor input, sufficient to avoid culpability — he will need to set out some national goals. If these include (as they seem to) a united, federated Iraq and the defeat of ISIS, Obama must make these objectives clear to Americans, do what is necessary to achieve them — and avoid a walk on the South Lawn.

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