WASHINGTON - U.S. warplanes continued to launch air strikes near the Mosul Dam today in support of a Kurdish and Iraqi ground operation to retake Iraq's largest dam from the control of hundreds of ISIS fighters.

Seizing back the dam has been a concern for Iraq and the United States because a breach could release a torrent of water that could flood Mosul and possibly reach as far downstream as Baghdad.

President Obama cited that threat in a letter sent to Congressional leaders today notifying them that he had authorized the airstrikes as being "in the national security and foreign policy interests of the United States."

"The failure of the Mosul Dam could threaten the lives of large numbers of civilians, endanger U.S. personnel and facilities, including the U.S. Embassy in Baghdad, and prevent the Iraqi government from providing critical services to the Iraqi populace," Obama said in the letter.

Obama said the strikes that began Friday evening will be limited in their scope and duration as necessary to support the Iraqi forces in their efforts to retake and establish control of this critical infrastructure site as part of the fight against the militant ISIS group that has seized major portions of northern and western Iraq.

A National Security Council spokesperson said the new mission was consistent with the presidential authorization issued last week to allow airstrikes to protect U.S. personnel and facilities anywhere in Iraq

A mix of fighters, bombers and Predator drones conducted 14 airstrikes today near the dam that targeted ISIS vehicles and positions. On Saturday, U.S. Central Command had launched nine airstrikes on the first day of the operation.

The combined 23 airstrikes over two days is almost equal to the same number of strikes conducted by U.S. military aircraft over the previous week. The significant ramp-up in airstrike operations reflects the scope of the effort to seize the dam from a significant force of ISIS fighters.

A U.S. official familiar with the operation said that there are a few hundred ISIS fighters at the dam.

The strikes "damaged or destroyed 10 ISIL [ISIS] armed vehicles, seven ISIL Humvees, two ISIL armored personnel carriers, and one ISIL checkpoint," according to a statement released by U.S. Central Command.

Centcom released two videos showing airstrikes conducted Saturday near the Mosul Dam. One video showed a strike against an ISIS armed truck, the second video showed a strike against a Humvee truck being used by ISIS fighters.

The armored vehicles being used by ISIS fighters indicates how well equipped the militants have become using American-made weapons and vehicles they seized from fleeing Iraqi security forces when they captured Mosul earlier this summer.

The release said all of the airstrikes have been conducted under authority granted by President Obama " to support humanitarian efforts in Iraq, as well as to protect critical infrastructure, U.S. personnel and facilities, and support Iraqi security forces and Kurdish defense forces" who are working to defeat ISIS.

The addition of bomber aircraft to the existing mix of F-15Es, F-16s, F/A-18s and Predator drones indicates the growing number of aircraft being dedicated to the push to retake the dam.

U.S. airstrikes are expected to continue as Kurdish forces seize land areas and villages located near the dam. Citing a Kurdish commander, The Associated Press reported today that Kurdish forces had retaken the eastern portion of the dam and that fighting continued.

Seizure of the dam would be a significant victory for Kurdish and Iraqi forces against ISIS militants, who have seized wide areas of northern and western Iraq.