WASHINGTON (AP) — U.S. fighters dropped bombs on Islamic militants in Iraq Friday, the Pentagon said, carrying out President Barack Obama's promise of military force to counter the advancing militants and confront the threat they pose to Iraqi civilians and Americans still stationed there. 
 
 FILE - This June 20, 2007, file photo shows a C-130-J transport aircraft over Little Rock Air Force Base in Jacksonville, Ark. President Barack Obama authorized U.S. airstrikes in northern Iraq, Thursday,... (Associated Press) 
 
 President Barack Obama approaches the podium to speak about the situation in Iraq in the State Dining Room at the White House in Washington, Thursday, Aug. 7, 2014. Obama says he has authorized the U.S.... (Associated Press) 
 
 President Barack Obama speaks about the situation in Iraq in the State Dining Room at the White House in Washington, Thursday, Aug. 7, 2014. Obama says he has authorized the U.S. military to launch targeted... (Associated Press) 
 
 President Barack Obama speaks about the situation in Iraq in the State Dining Room at the White House in Washington, Thursday, Aug. 7, 2014. Obama says he's authorized the U.S. military to carry out airstrikes... (Associated Press) 
 
 President Barack Obama speaks about the situation in Iraq in the State Dining Room at the White House in Washington, Thursday, Aug. 7, 2014. (AP Photo/Charles Dharapak) (Associated Press) 
 
 Pentagon press secretary Rear Adm. John Kirby said that two F/A-18 jets dropped 500-pound bombs on a piece of artillery and the truck towing it. Kirby said the fighters had taken off from the aircraft carrier USS George HW Bush in the Persian Gulf to conduct the mission. He said it wasn't clear how many militants might have been killed in the strike. 
 
 The Pentagon said the militants were using the artillery to shell Kurdish forces defending Irbil. 
 
 For the United States, it was a re-engagement in the long sectarian war from which American combat forces had been withdrawn — on President Barack Obama's orders — in late 2011. 
 
 In a televised speech Thursday night, Obama threatened to renew U.S. military involvement. At the same time, he announced that U.S. military planes already had carried out airdrops of food and water, at the request of the Iraqi government, to tens of thousands of Iraqi religious minorities atop a mountain surrounded by militants and desperately in need of supplies. 
 
 "America is coming to help," Obama declared. 
 
 Speaking to reporters while traveling in India Friday, Defense Secretary Chuck Hagel said the U.S. military has sufficient intelligence resources and assets in place to launch strikes by both manned and unmanned aircraft in the region. 
 
 Asked if the Islamic State group could successfully hide among civilians to evade strikes, Hagel said if the Islamic State moves against Irbil, Baghdad or the refugees trapped on a mountain, "it's pretty clear who they are, and they would be pretty identifiable where our airstrikes could be effective." 
 
 The Yazidis, who follow an ancient religion with ties to Zoroastrianism, fled their homes after the Islamic State group issued an ultimatum to convert to Islam, pay a religious fine, flee their homes or face death. 
 
 "Earlier this week, one Iraqi in the area cried to the world, 'There is no one coming to help.' Well, today, America is coming to help," Obama said. "We're also consulting with other countries — and the United Nations — who have called for action to address this humanitarian crisis." 
 
 The announcement reflected the deepest American engagement in Iraq since U.S. troops left. 
 
 Obama, who made his remarks in a steady and somber tone, has staked much of his legacy as president on ending what he once called the "dumb war" in Iraq. 
 
 Mindful of the public's aversion to another lengthy war, Obama acknowledged that the prospect of a new round of U.S. military action would be a cause for concern among many Americans. He vowed anew not to put American combat troops back on the ground in Iraq and said there was no U.S. military solution to the crisis. 
 
 "As commander in chief, I will not allow the United States to be dragged into fighting another war in Iraq," Obama said. 
 
 Even so, he outlined a rationale for airstrikes in the event the Islamic State militants advanced on American troops in Irbil and the U.S. consulate there in the Kurdish region of Iraq. The troops were sent to Iraq earlier this year as part of the White House response to the extremist group's swift movement across the border with Syria and into Iraq. 
 
 "When the lives of American citizens are at risk, we will take action," Obama said. "That's my responsibility as commander in chief." 
 
 He said he had also authorized the use of targeted military strikes if necessary to help the Iraqi security forces protect civilians. 
 
 The Pentagon said the airdrops were performed by one C-17 and two C-130 cargo aircraft that together delivered a total of 72 bundles of food and water. They were escorted by two F/A-18 fighters from an undisclosed air base in the region. 
 
 The planes delivered 5,300 gallons of fresh drinking water and 8,000 pre-packaged meals and were over the drop area for less than 15 minutes at a low altitude. 
 
 The president cast the mission to assist the Yazidis as part of the American mandate to assist around the world when the U.S. has the unique capabilities to help avert a massacre. 
 
 In those cases, Obama said, "we can act carefully and responsibly to prevent a potential act of genocide." 
 
 Officials said the U.S. was prepared to undertake additional humanitarian airdrops if necessary, though they did not say how quickly those missions could occur. 
 
 Administration officials had said earlier they believed unilateral U.S. strikes would be consistent with international law, in part because the Iraqi government has asked for Washington to take military action. They also said Obama had the constitutional authority to act on his own in order to protect American citizens. 
 
 Obama had similarly authorized strikes in Syria last summer after chemical weapons were deployed, but those attacks were never carried out, in part because of domestic political concerns and also because an international agreement to strip Syria of its stockpiles of the deadly gases. 
 
 The president has also faced persistent calls to take military action in Syria on humanitarian grounds, given that more than 170,000 people have been killed there. 
 
 Critics, including some Republicans in Congress, have argued that Obama's cautious approach to Syria has allowed the Islamic State group to flourish there, growing strong enough to move across the border with Iraq and make swift gains. 
 
 Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina praised Obama's proposed actions Thursday night but said much more will be necessary. 
 
 "This should include the provision of military and other assistance to our Kurdish, Iraqi and Syrian partners" who are fighting the militants, airstrikes against the militants' leaders and forces and support for Sunni Iraqis who seek to resist the extremists, they said in a statement. 
 
 In light of the militants' advances, Obama dispatched about 800 U.S. forces to Iraq earlier this year, with those troops largely split between joint operation centers in Baghdad and Irbil. 
 
 More than half are providing security for the embassy and U.S. personnel. American service members also are involved in improving U.S. intelligence, providing security cooperation and conducting assessments of Iraqi capabilities. 
 
 ___ 
 
 Associated Press writers Josh Lederman and Darlene Superville contributed to this report. 
 
 ___ 
 
 Follow Julie Pace at http://twitter.com/jpaceDC and Robert Burns at http://twitter.com/RobertBurnsAP ||||| Story highlights U.S. makes another drop of food and water to Iraqis stranded on mountain 
 
 Fighter jets and drones targeted an ISIS mortar position and a convoy, Pentagon says 
 
 The warplanes targeted an ISIS convoy near Irbil, the Pentagon says 
 
 ISIS militants capture dam north of Mosul, Kurdish official says 
 
 U.S. fighter jets and drones repeatedly bombed Sunni Islamic extremists in northern Iraq on Friday, targeting what officials described as ISIS artillery units and convoys advancing on the Kurdish regional capital of Irbil. 
 
 The airstrikes ramped up America's involvement in Iraq where ISIS, which calls itself the Islamic State, is seizing control of towns and key infrastructure in an advance that has forced hundreds of thousands to run for their lives. 
 
 The critical Mosul Dam is now in the hands of ISIS fighters, authorities said, while 150 hundred miles to the east tens of thousands of Iraq's minority Yazidis were trapped on a mountain by ISIS fighters below who vowed to kill them. 
 
 News of the second round of U.S. airstrikes came just after the governor of Irbil told CNN that ISIS may be as close as 30 kilometers (just over 18 miles) from the city of more than a million people. 
 
 The airstrikes began just hours after President Barack Obama authorized "targeted airstrikes," saying in a televised address late Thursday that the United States had an obligation to protect its personnel in Iraq and prevent a potential genocide of minority groups by ISIS. 
 
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 Obama said there will be no buildup of U.S. combat troops in Iraq. "As commander in chief, I will not allow the United States to be dragged into fighting another war in Iraq," the President said. 
 
 Hitting ISIS 
 
 Two U.S. F/A 18 fighters first struck an ISIS artillery unit outside of Irbil, dropping two 500-pound laser-guided bombs at about 6:45 a.m. ET Friday, Pentagon spokesman Navy Rear Adm. John Kirby said. 
 
 Later, a drone targeted an ISIS mortar position, Kirby said. When ISIS fighters returned to the site a short time later, the drone struck the target again, he said. 
 
 That was followed a short time later by a second round of airstrikes, carried out by four U.S. fighter jets, that targeted an ISIS convoy of seven vehicles and another mortar position, Kirby said. 
 
 The F/A 18s made two passes, dropping a total of eight laser-guided bombs, he said. 
 
 Before the ISIS onslaught, the region had been the most stable in Iraq and a cooperative ally of the United States. U.S. military advisers and consular personnel are stationed in Irbil. 
 
 At this point, the United States has hundreds of military personnel in Iraq, including advisers sent in recent weeks to coordinate with Iraqi and Kurdish military officials in response to the ISIS rampage. The USS George H.W. Bush and other Navy ships also are in the region, and the FA/18s in Friday's initial strike came from the aircraft carrier, officials said. 
 
 Airstrikes are "very important" because ISIS fighters are well-armed and are outgunning the Kurdish forces, thanks to the weapons the militants seized from the Iraqi military in Mosul, Irbil Gov. Nawzad Hadi said. 
 
 Even as the airstrikes were under way, there was news that ISIS militants captured Iraq's largest hydroelectric dam, just north of Mosul, Iraq's second-largest city. According to a senior Kurdish official, the militant fighters have been using U.S.-made weapons seized during fighting from the Iraqi army, including M1 Abrams tanks. 
 
 There had been conflicting reports about who controlled the dam on the Tigris River, with heavy fighting under way between ISIS fighters and Kurdish forces, known as peshmerga. U.S. officials have warned that a failure of the dam would be catastrophic, resulting in flooding all the way to Baghdad. 
 
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 In other fighting, an Iraqi airstrike killed 45 ISIS fighters and injured 60 Friday in the northern town of Sinjar, the country's state-run National Media Center said. 
 
 Sinjar is the town that ISIS overran last weekend, forcing tens of thousands of Yazidis to flee into surrounding mountains without food, water or shelter and prompting concerns of a potential genocide. The Yazidis are of Kurdish descent, and their religion is considered a pre-Islamic sect that draws from Christianity, Judaism and Zoroastrianism. 
 
 U.S. flights prohibited 
 
 In other signs of a growing regional conflict: The Federal Aviation Administration issued a notice prohibiting U.S. airlines from flying through Iraqi airspace "due to the hazardous situation created by the armed conflict." 
 
 The developments showed that the lightning advance by ISIS fighters across northern Iraq this year has become a battle for the nation's future and overall stability in a part of the world wracked for decades by periodic war. 
 
 U.S. warplanes patrolling the skies over northern Iraq have a "green light" to go after perceived ISIS threats to the Kurdish capital, Irbil, or to minority populations, said deputy national security adviser Ben Rhodes. 
 
 Airstrikes are also possible to help Kurdish forces end the siege by ISIS in the northern Iraqi mountains, where tens of thousands of Yazidis have sought refuge, Earnest, the White House spokesman, said Friday. 
 
 ISIS fighters have surrounded the Yazidis on the ground below. 
 
 "If there can be American military might that can tip (the) balance, we'll look for an opportunity to do that," Earnest said. 
 
 Kurdish pleas 
 
 In announcing his airstrike decision Thursday night, Obama said the militants would get hit "should they move towards the city." 
 
 Kurdish leaders have been pleading for the United States or NATO to buttress their forces against ISIS from the air. The President seems to have heard their appeal. 
 
 "We do whatever is necessary to protect our people," Obama said, adding, "We support our allies when they're in danger." 
 
 Before Obama announced the airstrikes, two U.S. military cargo planes airdropped 5,300 gallons of water and 8,000 meals onto Mount Sinjar, where some Yazidi children had died from dehydration. 
 
 U.S. F/A-18 E/F Super Hornet 
 
 Photos: U.S. military's fighter fleet Photos: U.S. military's fighter fleet An F/A-18E Super Hornet from the Sunliners of Strike Fighter Squadron 81 taxis onto a catapult before launching from the flight deck of the aircraft carrier USS Carl Vinson. Hide Caption 1 of 9 Photos: U.S. military's fighter fleet An F-15E Strike Eagle was designed for long-range, high-speed interdiction without relying on escort or electronic warfare aircraft. It was derived from the F-15 Eagle, which was developed to enhance U.S. air superiority during the Vietnam War. Hide Caption 2 of 9 Photos: U.S. military's fighter fleet A F-22 Raptor flies over Marietta, Georgia, home of the Lockheed Martin plant where it was built. The F-22 is the only fighter capable of simultaneously conducting air-to-air and air-to-ground combat missions. Hide Caption 3 of 9 Photos: U.S. military's fighter fleet F-16 Fighting Falcons are parked at the Aerospace Maintenance and Regeneration Center in Tucson, Arizona, on December 11, 2004. General Dynamics (which was later sold to Lockheed) delivered the U.S. Air Force its first F-16As in 1979. More than 4,500 of the fighters have been built, and they are used by more than 20 nations in addition to the United States. Hide Caption 4 of 9 Photos: U.S. military's fighter fleet A F-35C conducts a test flight over the Chesapeake Bay on February 11, 2011. Inspections of F-35 engines have been ordered after a runway fire at Eglin Air Force Base on June 23. The F-35 Lightning II has been beset by delays and cost overruns in the years since its introduction. Hide Caption 5 of 9 Photos: U.S. military's fighter fleet An A-10 Thunderbolt II from the 52nd Fighter Wing, 81st Fighter Squadron, Spangdahlem Air Base, Germany, in flight during a NATO Operation Allied Force combat mission. Hide Caption 6 of 9 Photos: U.S. military's fighter fleet An F/A-18 Hornet is pictured aboard the USS George H.W. Bush on May 19, 2009. The F/A-18 Hornet, a late-'70s contemporary of the Air Force's F-16 Fighting Falcon, became the workhorse of U.S. carrier-based air power and still supplements the Navy's and Marines' more current fleet of F/A-18E and F/A-18F Super Hornets. It is designed as both a fighter and an attack aircraft. Hide Caption 7 of 9 Photos: U.S. military's fighter fleet Pilots perform daily flight checks on their F-5E/F Tiger aircraft in Key West, Florida, on January 7, 2005. The Vietnam-era aircraft -- one of several offshoots of the original Northrup F-5s that went into service in the early 1960s -- is used to simulate adversary aircraft in training. Hide Caption 8 of 9 Photos: U.S. military's fighter fleet A AV-8B Harrier lands on board the USS Nassau on April 14, 1999, after a strike mission into Kosovo. The AV-8B Harrier is a single-engine ground-attack aircraft capable of vertical or short takeoff and landing. Though production of the aircraft ceased in 2003, the U.S. Marine Corps is looking at systems enhancements and plans to continue using Harriers well into the next decade. Hide Caption 9 of 9 
 
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 According to a U.S. official, a Predator drone flying overhead indicates the Yazidis have 63 of the 72 pallets dropped with aid supplies. It's not clear if the other pallets missed the drop zone or are in ISIS hands. 
 
 Late Friday, the Defense Department announced that U.S. military planes made another airdrop of food and water for Iraqi citizens stranded on Mount Sinjar. 
 
 The British government said Friday it would support the U.S. humanitarian effort and planned airdrops of its own. 
 
 French President François Hollande joined the growing chorus of condemnation of the ISIS attacks and called on the international community to respond. 
 
 "France is ready to take its part," Hollande said in a statement from his office that called for the European Union "to take an active role very quickly" and put in place all the necessary assistance to respond to the crisis. 
 
 Meanwhile, the United Nations in Iraq was "urgently preparing a humanitarian corridor to allow those in need to flee the areas under threat," said Nickolay Mladenov, the special representative to the U.N. secretary-general. 
 
 He welcomed the "cooperation between the Government of Iraq, the Kurdistan Regional Government (KRG) and the international community to help prevent genocide and fight terrorism," according to a U.N. statement. 
 
 Iraqi Foreign MInister Hoshyar Zebari told reporters Friday from Irbil that his government is working with the KRG -- including supplying the Kurdish peshmerga with ammunition and military helicopters. 
 
 This hasn't always been the case "because of political issues," the KRG's official website notes. Yet the same site reported that Zebari said "it is now clear that the peshmerga and the Iraqi security forces are fighting together against a common enemy." 
 
 Beheadings 
 
 ISIS has executed people who don't share their fanatical interpretation of Sunni Islam and posted videos of their killings to the Internet. "Convert to Islam or die" is the militants' ultimatum to those captured. 
 
 They also have beheaded victims and placed their heads on spikes to strike terror in the population, a senior administration official said. 
 
 Already, the Obama administration is rapidly funneling weapons to Iraqi forces. Factories are operating seven days a week to produce them, a senior administration official said. 
 
 The administration has pushed for Iraqi Prime Minister Nuri al-Maliki's Shiite-dominated regime to be replaced by an ethnically more inclusive government 
 
 But two Republican senators said in a statement that the President's actions do not go far enough. And the United States should not wait on Iraq to pull together before Washington takes action. 
 
 Sens. John McCain of Arizona and Lindsey Graham of South Carolina want to see U.S. forces take the fight to ISIS. 
 
 "It should include U.S. airstrikes against ISIS leaders, forces, and positions both in Iraq and Syria," their statement read. ||||| In a statement made Thursday night, President Obama said he has authorized military strikes on Islamic State militants if they continue their advancement on the city of Irbil, where military personnel and the U.S. consulate are located. (AP) 
 
 President Obama said Thursday night that he has authorized two new, major actions by the U.S. military in Iraq: airstrikes against militants with the Islamic State if U.S. interests or personnel are threatened, and humanitarian assistance for thousands of civilians who have fled the Islamist advance in northwest Iraq and are now trapped on a mountain. 
 
 Even those two specific missions are more complicated than that, however. 
 
 First, the U.S. humanitarian mission on Mount Sinjar began Thursday with airdrops by military aircraft, but it could require targeted airstrikes in order to “break the siege” at the base of the mountain and allow authorities to provide more assistance to the civilians, Obama said. They would be conducted in coordination with the Iraqi government and Iraqi Kurdish security forces known as pesh merga. 
 
 Second, the advance of the Islamic State near Irbil appears to be a line in the sand for the Obama administration. The United States has both diplomats and military advisers in the city, which is the capital of the Kurdistan region of Iraq. The United States also has a consulate in Irbil, creating enough interests that the United States wants to protect the city from harm. 
 
 “To stop the advance on Irbil, I’ve directed our military to take targeted strikes against [Islamic State] terrorist convoys should they move toward the city,” Obama said. “We intend to stay vigilant, and take action if these terrorist forces threaten our personnel or facilities anywhere in Iraq, including our consulate in Irbil and our embassy in Baghdad.” 
 
 
 
 In this image released by The White House, President Obama meets with the National Security Council in the Situation Room of the White House on Thursday in Washington. (AP Photo/The White House, Pete Souza) 
 
 Here’s what we know now about the specifics of these missions: 
 
 Humanitarian air drops 
 
 The U.S. military launched one C-17 and two C-130 cargo planes near Mount Sinjar on Thursday, dropping 8,000 prepackaged meals and 5,300 gallons of water, senior U.S. officials said. The aircraft were accompanied by two F/A-18 fighter jets, which came out of an undisclosed air base in the Middle East. The Pentagon did not indicate which units or branch of service operated any of the aircraft. 
 
 Pentagon officials said in a statement that the three cargo planes released a total of 72 bundles of supplies. They flew over the drop area for less than 15 minutes, and left the area before Obama announced the actions in his 9:30 p.m. address. 
 
 Senior U.S. officials left open the possibility that the United States could conduct more airdrops in coming days if it’s needed. That appears possible, considering human rights workers have estimated that up to 40,000 civilians may be trapped on the mountain, unable to return their homes for fear of being killed by militants. 
 
 “We feel that this is a unique and urgent humanitarian challenge,” one senior officials said Thursday night. 
 
 
 
 This image made from video taken on Sunday shows Iraqis people from the Yazidi community arriving in Irbil in northern Iraq after Islamic militants attacked the towns of Sinjar and Zunmar. Around 40,000 people crossed the bridge of Shela in Fishkhabur into the northern Kurdish region of Iraq after being given an ultimatum by Islamic militants to either convert to Islam, pay a security tax, leave their homes, or die. (AP Photo via AP video) 
 
 Preparing for airstrikes 
 
 The advance of militants across northern Iraq has been watched closely this week, but a new wave of attacks threatened Irbil in a way it had not been before, U.S. officials said. That led the president to authorize airstrikes if necessary. 
 
 U.S. officials also said that with the increased threat now facing Irbil, the United States has either surveillance drones or manned aircraft flying over the area almost constantly, keeping tabs on militant movements. 
 
 Defense Secretary Chuck Hagel said in a statement Thursday night that U.S. military advisers in Iraq will continue to assess ways to help train and assist Iraqi forces, and will provide undisclosed “increased support” once Iraq has formed a new government. Most of the troops there are U.S. Army Special Forces. 
 
 Outgoing Iraqi Prime Minister Nouri al-Malikihas faced fierce criticism for appointing friends to key positions, allowing corruption and cutting Iraq’s Sunni population out of the political process, fueling the insurgency. A new prime minister could be selected in coming days, U.S. officials signaled Thursday night. 
 
 UPDATED, Friday, Aug. 8, 9 a.m.: U.S. airstrikes in Iraq have begun after militants launched artillery rounds at Kurdish troops defending Irbil. Rear Adm. John Kirby, the Pentagon press secretary, posted this tweet:
– The US launched airstrikes against Iraq's Islamic State militants this morning. "US military aircraft conduct strike on ISIL artillery," tweeted Rear Adm. John Kirby. "Artillery was used against Kurdish forces defending (Irbil), near US personnel." He confirms that F/A-18 jets dropped a pair of laser-guided 500-pound bombs on militants towing artillery at about 6:45am Eastern, reports the AP. US military trainers are stationed nearby. More: The F/A-18s were based on the aircraft carrier USS George HW Bush in the Persian Gulf and took off on the orders of the commander of US Central Command, CNN reports. (President Obama authorized airstrikes last night.) It's unclear how many militants were killed in the strikes. John Kerry, speaking today in Afghanistan, echoed Obama's language, saying the Islamic State's "campaign of terror against the innocent, including the Yazidi and Christian minorities, and its grotesque targeted acts of violence show all the warning signs of genocide." Meanwhile, the AP reports that Iraqi and Kurdish officials are welcoming last night's humanitarian aid drops for Iraqis trapped by the militants in the mountains. "We thank Barack Obama," said one Kurdish official in northern Iraq, while a rep for the Iraqi Ministry of Migration and Displacement said the drops were "just in time."