The Obama administration is weighing options for an imminent response to the crisis in Iraq, including airstrikes against Islamic extremists who have overrun Iraqi cities to within striking distance of Baghdad, and expanded intelligence and targeting assistance for Iraqi military forces.

In the face of rapid extremist advances and the collapse of Iraqi military defenses in the north, the administration has decided temporarily to put aside its long-term goal of pressing Prime Minister Nouri al-Maliki for political reforms in favor of immediate action to stabilize the security situation.

Asked whether he was considering drone strikes, President Obama, who held a principals’ meeting with senior national security aides Thursday, said a number of options were being considered. “It’s fair to say . . . there will be some short-term, immediate things that need to be done militarily,” he added.

A senior administration official, who spoke on condition of anonymity to discuss the deliberations, said: “We are definitely looking at this with urgency.”

U.S. contractors began evacuating the air base in Balad, 50 miles north of Baghdad, that is being prepared for the arrival this year of F-16 aircraft purchased by Iraq. The international engineering and electronics company Siemens was trying to move 51 people out of Baiji, about 30 miles farther north, where they are upgrading Iraqi power plants.

The State Department confirmed that “U.S. citizens, under contract to the Government of Iraq, in support of the U.S. Foreign Military Sales (FMS) program in Iraq, are being temporarily relocated by their companies due to security concerns in the area.” But “the status of the staffing at the U.S. Embassy and consulates has not changed,” spokeswoman Jen Psaki said.

About 10,000 American officials and contractors are in Iraq.

Iraqi media and a source close to Maliki’s office in Baghdad said that Obama had already agreed to “imminent” U.S. airstrikes, to be launched from a base in Turkey. The senior official described those reports as “premature” but said a decision could come “today, tomorrow, in the coming days.”

The official confirmed close U.S. consultations with the government of Turkey, which shares a border with Iraq, and with Iraq’s Kurdish regional government, which has deployed its own forces to guard roads and cities in and near its northern region.

A number of lawmakers said they expected Obama to consult with Congress before taking any direct action. “It would depend on what the option is,” the senior official said. “That is very hypothetical. . . . There have not been discussions on that.” While the official noted that the president can take urgent action for up to 60 days without asking Congress under the War Powers Act — a provision the administration used for its brief Libya bombing campaign in 2011 — “that’s notional, and I don’t want to suggest” any decision has been made.

Maliki’s government requested strikes from drones or piloted aircraft “in the last several weeks” and additional intelligence-sharing as militants from the Islamic State of Iraq and Syria stepped up attacks in Iraq, according to the official. As long as there is an invitation from the sovereign government, the United States does not need United Nations approval to act.

Those requests were repeated and amplified as ISIS militants seized Mosul, Iraq’s main northern city, on Tuesday and began moving southward. Officials and experts on the region said they were more surprised at the speed with which the Iraqi military retreated than by the audacious ISIS assaults.

“The element of shock came in how quickly the Iraqi security forces seem to have folded,” said a senior Western diplomat, who spoke on the condition of anonymity because he was not authorized to comment publicly. “We were surprised by the minimal appetite to stand and fight, given that Iraqi forces are about a million strong and are well-equipped and trained by the United States, Britain” and others.

In comments made during an Oval Office meeting with Australian Prime Minister Tony Abbott, Obama said events this week should be “a wake-up call for the Iraqi government.” Since the U.S. military withdrawal in December 2011, the United States has been pushing Maliki, whose Shiite bloc won parliamentary elections in April, to reach out to alienated Sunnis and Kurds.

“That accounts in part for some of the weakness of the state, and that then carries over into their military capacity,” Obama said.

“There has to be a political component to this so that Sunni and Shia . . . inside of Iraq come together and work diligently against these extremists,” he said. “And that is going to require concessions on the part of both . . . that we haven’t seen so far.”

Over the past two years, the administration has tried to use security cooperation and sales of sophisticated equipment as a carrot to promote political reforms. But even as Maliki has made few, if any, moves in that direction, the security situation has forced the U.S. hand.

As suicide and other attacks increased in 2013 to the worst levels since the height of sectarian fighting during the U.S. occupation, Obama agreed during Maliki’s visit to Washington last fall to sell Iraqi Apache helicopters and F-16s — none of which have yet arrived in Iraq.

About 300 Hellfire missiles, which the Iraqis fire from their small fleet of Cessna Caravan turboprops, were urgently supplied, as well as small arms, ammunition and other equipment.

Early this year, about 100 U.S. Special Operations soldiers were sent to Jordan to train Iraqi counterterrorism forces. The administration has also increased its surveillance over Iraq, with unarmed drones, high-altitude flights, and satellites, as well as communications intercepts.

As the administration contemplated its next move, there was no shortage of critics Thursday who charged its military withdrawal from Iraq and subsequent alleged inattention, or its hesi­ta­tion to intervene in neighboring Syria’s civil war — or both — had precipitated the current crisis by allowing ISIS to grow.

“The Iraqis themselves opted not to keep U.S. forces” there, by refusing to sign a status of forces agreement in 2011, said James Jeffrey, who served as U.S. ambassador to Iraq for two years until mid-2012. “Obama pushed for it, but he didn’t push as far as he might.”

Whether a residual force in Iraq consisted of the 25,000 troops U.S. commanders originally requested, or the 2,500 Obama finally agreed to before the status agreement fell apart, it “would have given us a platform to do . . . the counterterrorism things we are so good at,” Jeffrey said. “We would have had some air power there, which would have been extremely effective against these guys [ISIS] who are out in the open with pickup trucks.

“We would have rotated in conventional battalions to train them to do exactly what they’re not doing now — small-unit tactics, fire-and-maneuver, platoon-level exercises.”

Most important, Jeffrey said, “we would have had Washington’s attention. . . . Whether it’s 5,000 or 2,000” troops, “believe me, all of Washington snaps to and salutes. The country reacts differently.”

The senior administration official defended Obama’s decision to “go slowly” in Syria. “The reason for being deliberate was precisely the need to have both an opposition that we knew was vetted and had . . . capacity” to absorb aid.

“Clearly, the Syrian conflict exacerbates and provides additional space for [ISIS] to operate,” the official said. “The Syrian conflict has been a symptom that has escalated the threat of these groups from Iraq, but certainly these groups existed long before that.”

After a closed-door briefing for the Senate Armed Services Committee by military and intelligence officials Thursday, some lawmakers urged caution.

Committee Chairman Carl Levin (D-Mich.), recalled the Bush administration’s invasion of Iraq in 2003, saying that “we got into Iraq without adequate consideration for the consequences.”

“What is required now is thoughtful consideration of our options, none of which, typically for the Middle East, is obvious or easy,” Levin said. “It’s important to keep in mind that a major source of Iraq’s problems has been the refusal of the Maliki government, despite persistent U.S. encouragement, to reach out to its Sunni citizens to forge a unified and inclusive Iraq. No action on our part can resolve that disunity. It’s unclear how airstrikes on our part can succeed unless the Iraqi army is willing to fight, and that’s uncertain given the fact that several Iraqi army divisions have melted away.”

Others, primarily Republicans, were harshly critical. “Iraq’s unraveling should come as no surprise,” Sens. John McCain (R-Ariz.) and Lindsey Graham (R-S.C.), said in a joint statement.

“We and others predicted that would happen as a result of the president’s decision to prematurely withdraw all American forces from Iraq.”