With aid of U.S. airstrikes, Kurdish forces retake control of Mosul Dam from ISIS

MOSUL, Iraq (CNN) -- U.S. airstrikes helped Kurdish and Iraqi forces take control of Mosul Dam on Monday, fighting back ISIS militants who had seized the dam, President Obama told reporters.

The stakes were huge for the millions of Iraqis who live downstream from the dam, the largest in the country.

"If that dam was breached, it could have proven catastrophic, with floods that would have threatened the lives of thousands of civilians and endangered our embassy compound in Baghdad," Obama said.



The dam has been the center of an intense battle in northern Iraq between the Islamic extremists and Kurdish forces that had been fighting to retake it since Saturday with U.S. air support.

"The U.S. military used fighters, bombers, attack and unmanned aircraft to conduct 35 strikes, " said Pentagon spokesman Rear Adm. John Kirby. "We destroyed over 90 targets, including a range of vehicles, equipment and fighting positions."

Now that the dam is cleared of ISIS militants, Iraqi forces are moving to grow their area of control, the Pentagon said.

"This operation demonstrates that Iraqi and Kurdish forces are capable of working together and taking the fight to ISIS," Obama said. "If they continue to do so, they will have the strong support of the United States of America."

Built in the early 1980s under former Iraqi dictator Saddam Hussein, the dam sits on the Tigris River about 30 miles north of the city of Mosul. It serves as a key source of electricity, irrigation and flood protection.

When ISIS militants seized the dam this month, many feared it could be used as a weapon.

Water in war

ISIS has a track record of attacking its enemies with water.

This year, its fighters opened the gates on the Falluja Dam in central Iraq after seizing it in an effort to stop an Iraqi military advance. The water from the dam flooded a number of villages.

"ISIS has already used other smaller dams to gain control of territory, to pressure Sunnis to support them and to punish the Shiites," Pipes said this month.

The 3.2-kilometer-long Mosul Dam holds back as much as 12.5 million cubic meters of water, according to Engineering News-Record, a construction industry website.

If the structure were to give way, it would unleash a wall of water tens of feet tall that would race down the Tigris toward Mosul and its 1.7 million inhabitants. It would also bring flooding to major cities farther downstream, including Baghdad.

'Very poor foundation'

But even if the militant group doesn't try to destroy the dam, concerns remain about its sturdiness.

A U.S. Army Corps of Engineers report in 2006 said that what made the dam especially dangerous was the risk of internal erosion of its foundations.

The structure is built on layers of soil that dissolve or erode in water.

The Army Corps said the dam was "constructed on a very poor foundation" that wasn't designed for the conditions.

Seepage has plagued the structure since the reservoir behind it was filled, according to a U.S. government report in 2007, and sinkholes have appeared near the structure, suggesting problems beneath the surface.

During the American military occupation of Iraq, U.S. authorities spent tens of millions of dollars on short-term repairs on the dam.

But with the immense structure now in the midst of a conflict zone, it remains unclear if it will get the maintenance it needs anytime soon.