US President Barack Obama makes a statement about the humanitarian relief situation in Iraq inside the Brady Press Briefing Room of the White House in Washington, August 7, 2014.[Photo/Agencies]

WASHINGTON -- US President Barack Obama says he's authorized the US military to carry out airstrikes in Iraq against Islamic militants if they advance toward the city of Erbil.

Obama says when the lives of Americans are at risk, and when thousands of civilians are at risk, US will take action.

"We can act, carefully and responsibly to prevent a potential act of genocide," Obama said, referring to a religious minority group besieged by fighters from the so-called Islamic State.

"I therefore authorized targeted air strikes if necessary to help forces in Iraq as they fight to break the siege and protect the civilians trapped there."