The increasingly dire straits of refugees in the Kurdish region of Iraq, amid startling gains by Islamist forces there, prompted the United States to launch airstrikes against the militants Friday in a major escalation of U.S. involvement in the crisis.

President Obama announced late Thursday that he had authorized the Pentagon to carry out the strikes if the extremists moved toward Irbil, the Kurdish regional capital, or continued to besiege Iraqi minorities who have fled the militants’ takeover.

The lightning-quick advance of the Islamic State militant group, south from the northern city of Mosul to within 60 miles of Baghdad, has been a source of deep concern since it began two months ago. But the administration worried that interjecting itself into the conflict would inevitably open it to charges of siding with one side or the other in what has become an increasingly sectarian battle.

With many Sunni Muslims seeing the Sunni militants as a better alternative than Shiite Prime Minister Nouri al-Maliki, the administration hoped to use the promise of additional military aid as leverage in promoting a new, more inclusive Iraqi government.

That strategy has been upended this week, however, as the Islamic State has turned its attention eastward to the semiautonomous Kurdish region it had largely circumvented in its march toward Baghdad.

View Graphic Map: U.S. airstrikes in Northern Iraq

On Thursday, outgunned and outnumbered Kurdish military forces, known as the pesh merga, retreated from a series of towns without fighting against the Islamist onslaught. Tens of thousands of desperate Iraqis from the Yazidi sect, stranded on a mountaintop without enough food and water, were surrounded by advancing Islamists.

There continues to be widespread agreement that no U.S. combat troops should be sent to Iraq. But use of U.S. air power has long been demanded by some lawmakers, who charge that a gun-shy and inattentive administration has allowed Islamists to make major gains in Syria and Libya, as well as Iraq, and has permitted Russia to directly challenge the sovereignty of Ukraine.

The administration has argued that military might, however much it has been a go-to solution of U.S. policy in the past — often with disappointing results — is not the answer to every problem. Instead, it has concentrated on diplomacy and building partnerships with local governments and security forces.

In Iraq, Obama has had the additional incentives of his own pledge to end the U.S. war in Iraq and the knowledge that the vast majority of the U.S. public is opposed to more military interventions in the Middle East.

Recent events have severely challenged that calculus, particularly in Iraq. “While America has never been able to right every wrong, America has been able to make the world a more secure and prosperous place,” Obama said in brief White House remarks on the crisis Thursday night. “I have been careful to reduce calls time and again to turn to our military,” he said. But “when lives of American citizens are at risk, we will take action.”

Iraqi Kurdistan has long been considered an ally and an island of stability and relatively good governance by U.S. policymakers. Its regional military forces were believed strong enough to resist Islamist encroachment.

But Kurdish officials — who have their own problems with Maliki — have been pleading for weeks for U.S. economic and military assistance as the region has been inundated with Iraqis fleeing militant takeovers in other parts of the country and Islamist forces have moved ever closer to Irbil, the Kurdish capital. The administration has resisted, saying that aid should go through the Iraqi government in Baghdad, if and when it gets organized.

Iraqi politician Vian Dakhil makes a raw, emotional plea for the protection of the Yazidi people before Iraqi parliament. (YouTube/Al Sumaria TV)

In a morning meeting of his national security aides Thursday morning, Obama reviewed the dire news from overnight and options for dealing with it. His principal Cabinet officers were absent — Secretary of State John F. Kerry was on an emergency visit to Afghanistan to deal with a separate crisis, and Defense Secretary Chuck Hagel was in India.

One senior administration official, speaking on the condition of anonymity about closed-door planning, said that discussion of U.S. intervention “advanced considerably over the past 24 hours.” News quickly circulated that the White House was considering “imminent” humanitarian airdrops to the Yazidis, and possible airstrikes against Islamist State targets.

By nightfall, Obama had decided to move ahead with the airdrops, and announced that he has authorized possible airstrikes, although Defense Department officials denied reports they had already begun.

In a briefing for reporters on the authorizations, a senior administration official said strikes would be “driven by military decisionmaking as to whether there are targets that present themselves.”

Although similar calls have been made for U.S. military action, specifically airstrikes, in Syria, the official said the presidential authorization applies only to Iraq. “This is not a broad-based campaign against” the Islamic State, he said. “We are not launching a sustained U.S. campaign. . . . Our belief is that the best way to deal with [the militants] is to over the long term let the Iraqis do it.”

The current situation in the Kurdish region has some similarities to what happened there in 1991, when ethnic Kurds revolted against oppression by the then-government of Saddam Hussein.

The United States, fresh from driving Hussein’s forces out of Kuwait in Operation Desert Storm, quickly intervened to rescue thousands of Kurdish refugees who had crowded along the Turkish border. Acting under a U.N. mandate, U.S. forces launched Operation Provide Comfort.

Operating out of Incirlik Air Base in Turkey, U.S. Air Force C-130s airdropped as many as 600 pallets of humanitarian supplies per day, according to an Air Force fact sheet, and eventually added ground forces to protect the Kurds. A U.S. military task force established a buffer zone along the southern border of the Kurdish region, protecting it from incursion by Hussein’s forces.

U.S. ground forces eventually withdrew, leaving protection of the Kurds to a no-fly zone and the constant patrol of U.S. aircraft that continued until the 2003 U.S. invasion of Iraq from the south and the overthrow of Hussein.

But the differences between 1991 and today are profound. The Kurdish region no longer shares a border with an Iraq run by the Maliki government. Instead, Islamic State forces are in control of the entire border region.

While the administration contemplates limited intervention, Earnest said, “There are no American military solutions to the problems in Iraq.”