BAGHDAD — For a second day, U.S. aircraft hammered Islamic State militants around the Mosul Dam on Sunday, as Kurdish forces progressed in efforts to retake the area.
The U.S. military launched 14 airstrikes around the dam Sunday, according to the U.S. Central Command. U.S. forces launched nine airstrikes targeting the region Saturday.
Kurdish forces recaptured some parts around the dam, but militants seeded the area with roadside bombs, making progress slow.
The new strikes suggest an incremental expansion of the U.S. mission, which began more than a week ago to prevent militants from overrunning Irbil, the capital of the Kurdish region, and to save Yaziri refugees trapped on a mountain to escape the Islamic State militants.
The air campaign around the dam has allowed Kurdish forces to begin retaking territory seized by the militants, also known as the Islamic State of Iraq and the Levant. The group shortened its name to the Islamic State.
President Obama sent a letter to Congress on Sunday explaining his authorization of the strikes.
"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 emphasized that the mission is limited in "scope and duration."
Militants seized the dam this month, gaining control over electricity distributed to much of northern Iraq and the capability to flood communities downriver.
The U.S. military used a mix of aircraft and drones in Sunday's strikes, destroying or damaging seven Humvees, two armored personnel carriers and a militant checkpoint.
The militants captured an array of U.S. military equipment from Iraqi forces in June when four divisions collapsed in Mosul after the radical forces attacked the city. The equipment gave Islamic State fighters an advantage in firepower, but they're vulnerable to attack from the air.