The White House on Sunday said President Barack Obama had informed Congress he authorized US air strikes in Iraq to help retake control of the Mosul Dam, and that the action was consistent with his goal of protecting US citizens in that country.
"The failure of the Mosul Dam could threaten the lives of large numbers of civilians, threaten US personnel and facilities - including the US embassy in Baghdad - and prevent the Iraqi government from providing critical services to the Iraqi populace," the White House said in a statement.
"These operations are limited in their nature, duration, and scope and are being undertaken in coordination with and at the request of the government of Iraq."
The Mosul Dam fell under the control of Islamic State militants earlier this month. Control of the dam, Iraq's biggest, could give the Sunni fundamentalists the ability to flood cities and cut off vital water and electricity supplies.
The US Central Command said on Sunday the United States conducted a second day of air strikes against Islamic State fighters near the dam, using a mix of fighter, bomber, attack and remotely-piloted aircraft.
Central Command said the 14 strikes on Sunday damaged or destroyed 10 armed vehicles, seven Humvees and two armored personnel carriers of the Islamic State as well as one of the militants' checkpoints. The strikes followed nine US air strikes on Saturday.
"All strike aircraft exited the strikes areas safely," Central Command said in a statement.
The Obama administration earlier this month launched an air strike campaign to protect US personnel from the Islamic State and to ensure northern Iraq's minority Yazidis were not subject to systematic violence at the hands of the militants.
The air strikes were the first direct US military action in Iraq since the end of 2011, when Washington completed the withdrawal of its troops from the country.
Iraq has been plunged into its worst violence since the peak of a sectarian civil war in 2006 and 2007. Islamic State-led fighters have overrun large parts of western and northern Iraq, forcing hundreds of thousands to flee for their lives and threatening ethnic Kurds in their autonomous province.
The Islamic State has also seized large parts of Syria as it tries to build a caliphate across national borders drawn up by Europeans a century ago.