Hoshyar Zebari, Iraq’s foreign minister, last year floated the idea that armed American-operated Predator or Reaper drones might be used to respond to the expanding militant network in Iraq. American officials dismissed that suggestion at the time, saying that the request had not come from Mr. Maliki. 
 
 By March, however, American experts who visited Baghdad were being told that Iraq’s top leaders were hoping that American air power could be used to strike the militants’ staging and training areas inside Iraq, and help Iraq’s beleaguered forces stop them from crossing into Iraq from Syria. 
 
 “Iraqi officials at the highest level said they had requested manned and unmanned U.S. airstrikes this year against ISIS camps in the Jazira desert,” said Kenneth M. Pollack, a former C.I.A. analyst and National Security Council official, who is a senior fellow at the Brookings Institution and who visited Baghdad in early March. ISIS is the acronym for the Islamic State in Iraq and Syria, as the militant group is known. 
 
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 As the Sunni insurgents have grown in strength those requests have persisted. In a May 11 meeting with American diplomats and Gen. Lloyd J. Austin III, the head of the Central Command, which oversees American military operations in the Middle East, Mr. Maliki said he would like the United States to provide Iraq with the ability to operate drones. But if the United States was not willing to do that, Mr. Maliki indicated he was prepared to allow the United States to carry out strikes using warplanes or drones. 
 
 In a May 16 phone call with Vice President Joseph R. Biden Jr., Mr. Maliki again suggested that the United States consider using American air power. A written request repeating that point was submitted soon afterward, officials said. 
 
 Some experts say that such American military action could be helpful but only if Mr. Maliki takes steps to make his government more inclusive. 
 
 “U.S. military support for Iraq could have a positive effect but only if it is conditioned on Maliki changing his behavior within Iraq’s political system,” Mr. Pollack said. “He has to bring the Sunni community back in, agree to limits on his executive authority and agree to reform Iraqi security forces to make them more professional and competent.” 
 
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 But so far, the administration has signaled that it is not interested in such a direct American military role. 
 
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 “Ultimately, this is for the Iraqi security forces, and the Iraqi government to deal with,” Rear Adm. John F. Kirby, the Pentagon spokesman, said Tuesday. 
 
 The deteriorating situation in Iraq is not what the Obama administration expected when it withdrew the last American troops from there in 2011. In a March 2012 speech, Antony J. Blinken, who is Mr. Obama’s deputy national security adviser, asserted that “Iraq today is less violent” than “at any time in recent history.” 
 
 From the start, experts have stressed that the conflict in Iraq is as much political as military. Mr. Maliki’s failure to include leading Sunnis in his government has heightened the sectarian divisions in Iraq. 
 
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 But American officials also say that militants from the Islamic State of Iraq and Syria represent a formidable military threat, one that Iraq’s security forces, which lack an effective air force, have been hard pressed to handle on their own. 
 
 The Islamic State of Iraq and Syria grew out of Al Qaeda in Iraq, the militant group that American forces fought during their war there. But while the capabilities of the militants have grown, the Iraq’s military’s effectiveness has diminished. 
 
 Adding to that challenge is the fact that the group controls territory on both sides of the Iraqi-Syrian border, and the Iraq and Syria conflicts have been feeding each other. 
 
 Said Lakhdar Brahimi, the former United Nations envoy to the collapsed Syria peace talks: “The region is in trouble, starting with Iraq. When I went to Baghdad in December, I was told that for every 100 operations ISIS did in Syria, it did 1,000 in Iraq.” 
 
 Critics say the latest developments show the weakness in an administration strategy designed to shore up Iraqi forces and to combat a growing Islamic militancy in Syria that officials say poses an increasing counterterrorism threat to the United States. 
 
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 In a speech on Wednesday, Susan E. Rice, Mr. Obama’s national security adviser, said that the American effort to buttress Iraq’s forces had been effective. “The United States has been fast to provide necessary support for the people and government of Iraq,” she said in remarks at the Center for New American Security in Washington. 
 
 The United States has provided a $14 billion foreign military aid package to Iraq that includes F-16 fighter jets, Apache attack helicopters and M-16 rifles. It has rushed hundreds of Hellfire missiles as well as ScanEagle reconnaissance drones. 
 
 A second round of counterterrorism training between American Special Operations commandos and Iraqi troops started in Jordan this week. At least two F-16s are set to arrive in Iraq by September, and six Apaches will be leased for training later this year, Iraqi and Pentagon officials said. 
 
 But some former generals who served in Iraq said a greater effort was needed. 
 
 James M. Dubik, a retired Army lieutenant general who oversaw the training of the Iraqi army during the surge, summed it up this way: “We should fly some of our manned and unmanned aircraft and put advisers into Iraq that can help the Iraqi Army plan and execute a proper defense, then help them transition to a counter offensive.” ||||| The aircraft assigned to dropping food and water over the mountainside were a single C-17 and two C-130 aircraft. They were escorted by a pair of F-18 jet fighters, the administration official said. The planes were over the drop zone for about 15 minutes, and flew at a relatively low altitude. They flew over the Mount Sinjar area for less than 15 minutes, Pentagon officials said, and dropped a total of 5,300 gallons of fresh drinking water and 8,000 meals ready to eat. Mr. Obama, officials said, delayed announcing the steps he intended to take in Iraq until the planes had safely cleared the area. 
 
 A senior administration official said that the humanitarian effort would continue as needed, and that he expected further airdrops. “We expect that need to continue,” he said. 
 
 The official said that as conditions in Iraq deteriorated in recent days, the United States had worked with Iraqi security forces and Kurdish fighters to coordinate the response to militant advances. The official said the cooperation had included airstrikes by Iraqi forces against militant targets in the north. 
 
 Kurdish and Iraqi officials said that airstrikes were carried out Thursday night on two towns in northern Iraq seized by ISIS — Gwer and Mahmour, near Erbil. Earlier on Thursday, The New York Times quoted Kurdish and Iraqi officials as saying that the strikes were carried out by American planes. 
 
 While the militants are not believed to have surface-to-air missiles, they do have machine guns that could hit planes flying at a low altitude, said James M. Dubik, a retired Army lieutenant general who oversaw the training of the Iraqi Army in 2007 and 2008. 
 
 “These are low and slow aircraft,” General Dubik said. At a minimum, he said, the United States must be prepared for “some defensive use of air power to prevent” the militants from attacking American planes, or going after the humanitarian supplies. 
 
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 For Mr. Obama, who has steadfastly avoided being drawn into the sectarian furies of the Middle East, the decision raises a host of difficult questions, injecting the American military into Iraq’s broader political struggle — something Mr. Obama said he would not agree to unless Iraq’s three main ethnic groups agreed on a national unity government. 
 
 The decision could also open Mr. Obama to charges that he is willing to use American military might to protect Iraqi Christians and other religious minorities but not to prevent the slaughter of Muslims by other Muslims, either in Iraq or neighboring Syria. 
 
 But the president said the imminent threat to Erbil and the dire situation unfolding on Mount Sinjar met both his criteria for deploying American force: protecting American lives and assets, and averting a humanitarian disaster. 
 
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 “When we have the unique capacity to avert a massacre, the United States cannot turn a blind eye,” he said. 
 
 Mr. Obama has been reluctant to order direct military action in Iraq while Prime Minister Nuri Kamal al-Maliki remains in office, but in recent weeks there have been repeated pleas from the Kurdish officials for weapons and assistance as ISIS militants have swept across northwestern Iraq. The militants, an offshoot of Al Qaeda, view Iraq’s majority Shiite and minority Christians and Yazidis as infidels. 
 
 Deliberations at the White House went on all day Thursday as reports surfaced that administration officials were considering either humanitarian flights, airstrikes or both. 
 
 Shortly after 6 p.m., the White House posted a photo of Mr. Obama consulting his national security team in the Situation Room. To his right was the chairman of the Joint Chiefs of Staff, Gen. Martin E. Dempsey. Watching from across the table were Susan E. Rice, the national security adviser, and her principal deputy, Antony J. Blinken. On the wall behind them, the clock recorded the time: 10:37 a.m. 
 
 Mr. Obama made only one public appearance, a rushed visit to Fort Belvoir, Va., where he signed into law a bill expanding access to health care for veterans. But aides suggested he might make a statement Thursday night. Before getting into his limousine, Mr. Obama was observed holding an intense conversation with his chief of staff, Denis R. McDonough, stabbing his finger several times for emphasis. 
 
 Later, Mr. McDonough telephoned the House speaker, John A. Boehner, to inform him of the president’s plans, and other White House officials spoke with lawmakers — all in an effort to avoid bruised feelings like those that followed the prisoner swap for Sgt. Bowe Bergdahl. 
 
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 Administration officials said on Thursday that the crisis on Mount Sinjar in northwestern Iraq had forced their hand. Some 40 children have already died from the heat and dehydration, according to Unicef, while as many as 40,000 people have been sheltering in the bare mountains without food, water or access to supplies. 
 
 Still, offensive strikes on militant targets around Erbil and Baghdad would take American involvement in the conflict to a new level — in effect, turning the American Air Force into the Iraqi Air Force. 
 
 “The White House is going to recognize that the need to commit air power to Iraq, even for a purely humanitarian mission, is going to open them up to greater criticism for their disengagement from Iraq,” said Kenneth M. Pollack, a senior fellow at the Brookings Institution. “So they will do their damnedest not to get further involved in Iraq because that would just further validate those criticisms.” 
 
 Ever since Sunni militants with ISIS took over Mosul, Iraq’s second-largest city, on June 10, Iraqis have feared that Baghdad, to the south, was the insurgents’ ultimate goal. But in recent weeks, the militant group has concentrated on trying to push the Kurds back from areas where Sunnis also live along the border between Kurdistan and Nineveh Province. 
 
 It has taken on the powerful Kurdish militias, which were thought to be a bulwark against the advance, and which control huge oil reserves in Kurdistan and broader parts of northern Iraq. An administration official said the United States would expedite the delivery of weapons to the Kurds. 
 
 For Mr. Obama, the suffering of the refugees on the mountainside appeared to be a tipping point. He spoke in harrowing terms about their dire circumstances, saying thousands of people were “hiding high up on the mountain, with little but the clothes on their backs.” 
 
 “They’re without food, they’re without water,” he said. “People are starving. And children are dying of thirst. These innocent families are faced with a horrible choice: descend the mountain and be slaughtered, or stay and slowly die of thirst and hunger.”
– The US rebuffed Iraq's request for airstrikes as insurgents gained strength, but American drones were already collecting intelligence on the militants. The secret drone program, carried out with the consent of the Iraqi government since last year, failed to predict the rapid advance of militants who have now seized several cities, officials tell the Wall Street Journal. "It's not like it did any good," one US official says. President Obama says "all the options" are being considered to help Iraq and while the use of ground troops has been ruled out, officials are considering expanding the drone program. The al-Qaeda-linked Islamic State of Iraq and Syria militants have vowed to take the fight to Baghdad, and although the capital is not expected to fall, Americans in Iraq are keeping an eye on the exit. Officials say they have stepped up plans for the evacuation of the US Embassy in Baghdad, and the BBC reports that American defense contractors working with the Iraqi military are being shifted to safer areas. Hundreds of contractors "are being temporarily relocated by their companies due to security concerns in the area," according to a State Department spokeswoman.