Zahko, Iraq (CNN) -- Kurdish forces, with the aid of U.S. airstrikes, on Saturday began weakening the grip that extremist militants hold over key piece of infrastructure in northern Iraq -- the Mosul Dam.
ISIS militants, who now call themselves the Islamic State, took over the dam earlier this month. In a 2007 report, U.S. officials warned that a failure of the dam would be catastrophic, resulting in flooding all the way to Baghdad.
ISIS has claimed a large swath of northern and western Iraq and parts of Syria, but its advance in Iraq has been met with resistance from Kurdish forces and U.S. airstrikes.
A colonel for the Pershmerga, as the Kurdish military force is known, told CNN that an operation to retake the Mosul Dam began early Saturday.
Peshmerga forces slowly advanced toward the dam from two areas in the north, and the U.S. carried out airstrikes on "mobile ISIS positions" on the western side of the dam, the colonel said.
The dam complex itself has not been hit, the Pershmerga colonel said. The dam is under ISIS control, but it is still up and running and engineers and employees remain at work, he said.
A Peshmerga spokesman denied that its forces had mobilized to retake the dam.
Hilgurd Hikmat confirmed that U.S. airstrikes inflicted "great losses" on ISIS targets, but claimed that Kurdish forces are not on the move and have not engaged in battle with ISIS near the dam.
The Peshmerga is coordinating with the U.S., he told CNN.
The Mosul Dam is Iraq's largest hydroelectric dam. It sits on the Tigris River about 50 kilometers (31 miles) north of Mosul, which fell to the extremist group in June when it swept from Syria into Iraq.
U.N. resolution targets ISIS
News of the airstrikes unfolded the same day the U.N. Security Council unanimously adopted a resolution aimed at curbing the support -- money and arms -- flowing to the al Qaeda splinter group that has aided its rapid and brutal advance across Iraq.
"It has seized some of the country's precious natural resources and taken control of critical infrastructure," Samantha Power, the U.S. representative, said, referring to ISIS.
"Now (ISIS) has the ability to block the flow of electricity and control access to the water supplies on which people depend."
The resolution sanctioned six people, described as financiers and supporters of ISIS' actions in Iraq and Syria, by freezing their assets and banning them from traveling.
While the resolution called for the use of economic sanctions and military force, if necessary, to ensure that ISIS militants "disarm and disband," it stopped short of authorizing the immediate use of U.N.-sanctioned military action against ISIS.
Under the resolution, a team charged with monitoring the activities of ISIS has been ordered to investigate the extremist group's resources, funding and recruitment and report back with recommendations to the Security Council within 90 days.
Yazidi men killed, women abducted
ISIS fighters swept into a Yazidi village in northern Iraq on Friday, killing at least 80 men and taking more than 100 women captive, officials told CNN.
The report of the brutal attack on the village of Kojo comes a day after U.S. President Barack 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.
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 cannot 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.