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 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. "As commander in chief, I will not allow the United States to be dragged into fighting another war in Iraq," the President said. On Friday the Pentagon said U.S. fighter jets had dropped 500-pound bombs on a piece of artillery and a truck towing it after it fired near U.S. personnel outside the city. (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. After seizing Iraq's second largest city Mosul in June, the Islamic State group advanced across the north, pushing back Kurdish forces and coming within 40 miles (60 kilometers) of Irbil. 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. "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." He said he had also authorized the use of targeted military strikes if necessary to help the Iraqi security forces protect civilians. 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. 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. "The condemnation and consolation statements in support of the affected people, or sending some humanitarian aid, is not enough. 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. In contrast to Washington's decision to invade Iraq more than a decade ago, both the airdrop and the authorization of military action against the Islamic State group were widely welcomed by Iraqi and Kurdish officials fearful of the militants' lightning advance across the country. 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.
– 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."