Like "shock and awe," but in reverse, a radical Islamic group rolled through huge swaths of Iraq last week and now effectively controls significant portions of the beleaguered country.

The offensive by the Islamic State of Iraq and Syria (ISIS) stopped just short of Baghdad, but the stop is likely just a pause, and the rekindled civil war in Iraq threatens to engulf the entire Mideast in the Sunni-Shiite divide that is playing out in Syria and elsewhere.

The rapid advance by ISIS seemingly has caught the Obama administration flat-footed — again. It's also understandably deeply distressing to Americans, especially those who fought there and those who lost loved ones during the war in Iraq, which started in 2003. Presidents George W. Bush and Obama have both been blamed, often along strictly partisan lines, for putting troops in (Bush) and prematurely pulling troops out (Obama).

This domestic debate is important, and will no doubt play out during this year's midterm election and especially in 2016, when a successor to Obama is chosen.

In the meantime, however, an international crisis is unfolding. And, although many Americans would like to retreat from the world, the world keeps finding ways to present grave choices that can have a direct and dire impact on U.S. national security.

Doing nothing may sound preferable, even rational, especially with pressing domestic concerns, a design to diplomatically "pivot" to Asia and the ongoing crisis in Ukraine, among other issues. But indecision is a decision in itself, as witnessed with Syria, where extremists filled the void created by Obama's reluctance to back more moderate forces trying to oust President Bashar Assad.

But this does not mean that the administration should rush headlong into using air power, as many in both the United States and Iraq have urged. First, it may be extremely difficult in the absence of actionable intelligence — the kind that is difficult to obtain without "boots on the ground," which Obama has ruled out. Second, any civilian casualties involving Sunnis would inflame that population, whose support is key to driving out ISIS.

To be sure, some Sunnis have abetted ISIS. But it's likely that their tacit acceptance of the militant group is based on opposition to the Iraqi government, which has discriminated against the minority Sunni population. In particular, Iraqi President Nouri al-Maliki is widely cited for exacerbating sectarian tensions through his economic, political and military policies.

The ideal would be for al-Maliki to resign. He has been a destructive political force and an incompetent military leader.

Short of resigning, al-Maliki should be pressured by allies, including the United States, to make way for a national unity government that would work with moderate Sunnis as well as with Iraq's Kurdish minority.

Such a government would not convince the nihilistic ISIS, which on Sunday boasted about the executions of 1,700 Iraqi troops. Rather, it would help convince Sunni leaders to try to eject ISIS, just as some Sunni "Awakening Councils" did against Al-Qaida during the Iraq war. Only then should the Obama administration even consider any more military involvement.

"If we can at least prevent the further deterioration of the situation in the first instance, we can then play a longer game to help the Iraqis take Mosul," said Michael O'Hanlon, director of research for the Foreign Policy program at the Brookings Institution. "You may have to do this sequentially. It doesn't mean that the first step is unimportant; it just means it isn't decisive."

Convincing al-Maliki to change course won't be easy. He's on war footing. And he can rebuff Obama by turning to Iran, whose Shiite theocracy has close ties to al-Maliki's government despite the brutal Iran-Iraq War of the 1980s.

Anticipating this, the administration has floated the idea of cooperating with Iran, despite being on different sides on nearly every other Mideast conflict. If Obama chooses that course, it's imperative that any cooperation is separate from the ongoing negotiations over Iran's potential nuclear weapons program.

Obama, an opponent of the Iraq war who campaigned on ending it, is understandably and responsibly reluctant to get back in. But allowing a vast swath of Iraq to become in effect a terrorist haven may drag the United States back into Mesopotamia, let alone the broader Mideast, under even worse circumstances. Now is the time for deft diplomacy to address some of the root causes of Iraq's implosion, and to be extremely cautious in considering military action.