UPDATE —Aug. 8, 2014 3:56 p.m. ET:
The Pentagon confirmed the second round of air strikes against Islamic State targets to defend Irbil where U.S. personnel are located.
The Pentagon announced that the U.S. military conducted an airstrike against the militant Islamic group ISIS outside the city of Irbil at approximately 6:45 a.m. on Friday.
The strike was conducted against ISIS mobile artillery that was being used to shell Kurdish forces defending Irbil, where U.S. personnel are located.
Hours after President Obama authorized air strikes against the Islamic State extremist group, two U.S. Navy F-18 fighter jets dropped two 500 lb laser-guided bombs on mobile artillery that was being used by ISIS forces outside the city of Irbil in northern Iraq.
According to Pentagon press secretary Rear Admiral John Kirby, ISIS militants were using the artillery to shell Kurdish forces defending the city of Irbil, which is home to American diplomatic and military personnel. He said it wasn't clear how many militants had been killed in the strike, the Associated Press reported.
Obama said Thursday that the military would take direct action against ISIS forces if their advances towards Irbil threatened U.S. personnel there.
The U.S. also authorized military strikes to protect tens of thousands of refugees belonging to the Yazidi religious minority, who are trapped on a barren mountain besieged by ISIS militants outside the northern town of Sinjar.
ISIS is an al-Qaeda linked group intent on creating an ultra-radical Islamist state in Iraq and Syria. Sunni fighters from ISIS have seized control of several towns and cities as they have swept through northern Iraq since June.