Baghdad , Iraq ( CNN ) -- U.S. warplanes on Saturday pounded a series of extremist militant targets in what officials say is part of an effort to retake a key piece of infrastructure in northern Iraq -- Mosul Dam . The airstrikes against fighters of the so-called Islamic State come amid growing concern that the dam is not being properly maintained and could rupture , a U.S. official familiar with the details told CNN . Engineering studies have shown that a failure of the dam would be catastrophic , resulting in flooding all the way to Baghdad , the official said on condition of anonymity . Mosul Dam is Iraq 's largest hydroelectric dam , and it sits on the Tigris Rivers about 50 kilometers ( 31 miles ) north of the city of Mosul . ISIS fighters took control of the dam this month following fierce fighting . The United States estimates there may be up to 400 ISIS fighters in and around the dam complex , said the U.S. official . The U.S. military confirmed a mix of fighter jets and drones carried out nine airstrikes near Mosul and the Kurdish regional capital of Irbil . The strikes targeted armored vehicles being used by ISIS fighters , it said . U.S. Central Command declined to provide further details , citing security of its personnel . Map : Where is ISIS ? There were conflicting reports from Kurdish officials about whether its military force , known as the Peshmerga , had begun a ground operation to retake the dam . Mosul Dam remains in hands of ISIS . A colonel with the Peshmerga told CNN the operation began early Saturday with Kurdish forces advancing toward the dam as the United States carried out airstrikes against `` mobile ISIS positions . '' The dam complex has not been hit , the colonel said on condition of anonymity . He is not authorized to speak to the media . While Peshmerga spokesman Hilgurd Hikmat also confirmed the U.S. airstrikes , he said the Kurdish forces are not on the move and have not engaged in battle with ISIS fighters near the dam . Mosul Dam is under ISIS control , but it is still up and running , the colonel said . Engineers and employees remain at work , he said . U.S. intelligence agencies , according to the U.S. official , are also keeping an eye on the Haditha Dam on the Euphrates River in Iraq 's western Anbar province , where Iraqi troops have been holding off an ISIS assault for weeks . The dam is the second-largest in the country , and it provides water to western and southern Iraq . A failure of the Haditha Dam also would prove catastrophic . Earlier this year , ISIS fighters opened the gates on the Falluja dam after seizing it in an effort to stop an Iraqi military advance . The water from the dam flooded a number of small villages . Opinion : In Iraq , it 's not 'mission creep ' U.S. President Barack Obama ordered targeted airstrikes to protect U.S. personnel and facilities in Iraq and prevent a potential genocide of ethnic and religious minority groups by ISIS , also known as the Islamic State in Iraq and Syria . American airstrikes were carried out near the Yazidi village of Kojo amid reports that ISIS fighters had launched an attack , the U.S. military said . Yazidi men killed , women abducted . ISIS swept into the village on Friday , killing at least 80 men and taking more than 100 women captive , officials told CNN . One Yazidi leader put the death toll much higher . The report of the brutal attack on the village of Kojo came after Obama -- citing the success of targeted American airstrikes -- declared an end to an ISIS siege that had trapped tens of thousands of Yazidis in mountains . Who are the Yazidis ? A Yazidi leader , Mirza Dinnayi , told British broadcaster Channel Four News that more than 350 men were killed and 1,000 women and children kidnapped during the attack . Fighters with ISIS attacked Kojo after surrounding it for days , a Kurdish regional government official and a Yazidi religious leader said . The women abducted from the village were being taken to the ISIS-controlled northern cities of Mosul and Tal Afar , the official said . CNN can not independently confirm the killings and abductions , but the claims are similar to reports provided by survivors of ISIS attacks in Iraq . The Yazidis , one of Iraq 's smallest and oldest religious minorities , are among 400,000 people that the United Nations estimates have been driven from their homes since June , when ISIS swept across the border from Syria into Iraq . After the rescue : A Yazidi family 's harrowing flight to escape ISIS . Jomana Karadsheh reported from Baghdad , Barbara Starr from Washington and Chelsea J. Carter reported and wrote from Atlanta . CNN 's Anna Coren , Mohammed Tawfeeq and Mariano Castillo contributed to this report .
NEW : Growing concern Mosul Dam is not being properly maintained by Kojo , U.S. official says . NEW : U.S. intelligence agencies are watching the Haditha Dam , the official says . U.S. fighter jets and drones carry out airstrikes near Kojo village and Kojo village , the U.S. military says . Earlier this year leader tells a British broadcaster the death toll in Kojo village is nine .