U.S. conducts airstrikes on ISIS militants in Iraq

Two U.S. F/A-18 jet fighters bombed artillery of Sunni Islamic extremists in Iraq on Friday, escalating America's military involvement more than two years after President Barack Obama brought home forces from the country.

Obama authorized "targeted airstrikes" if needed to protect U.S. personnel from fighters with ISIS, which calls itself the Islamic State. The U.S. military also could use airstrikes to prevent what officials warn could be a genocide of minority groups by the ISIS fighters.

Meanwhile, a senior Kurdish official told CNN that ISIS militants captured Iraq's largest hydroelectric dam, just north of Mosul, Iraq's second-largest city. According to the official, the militant fighters have been using U.S.-made weapons seized from the Iraqi army, including M1 Abrams tanks.

There had been conflicting reports about who controlled the dam on the Tigris River, with heavy fighting under way between ISIS fighters and Kurdish forces, known as Peshmerga. U.S. officials have warned that a failure of the dam would catastrophic, resulting in flooding all the way to Baghdad.

In other fighting, an Iraqi airstrike killed 45 ISIS fighters and injured 60 Friday in the northern town of Sinjar, the country's state-run National Media Center said.

Sinjar is the town that ISIS raided last weekend, causing members of the Yazidi minority there to flee into surrounding mountains without food, water or shelter and prompting concerns of a potential genocide.

U.S. flights prohibited

U.S. military's fighter fleet

U.S. starts aid drop mission in Iraq

Obama authorizes airstrikes against ISIS

Other signs of a growing regional conflict: The Federal Aviation Administration issued a notice prohibiting U.S. airlines from flying through Iraqi airspace "due to the hazardous situation created by the armed conflict."

The developments showed that the lightning advance by ISIS fighters across northern Iraq this year has become a battle for the nation's future and overall stability in a part of the world wracked for decades by periodic war.

French President François Hollande strongly condemned ISIS attacks against the Iraqi population and vulnerable minorities such as Yazidis and Christians and called for the international community to respond.

"France is ready to take its part," Hollande said in a statement from his office that called for the European Union "to take an active role very quickly" and put in place all the necessary ssistance to respond to the crisis.

U.S. warplanes patrolling the skies over northern Iraq have a "green light" to go after perceived ISIS threats to the Kurdish capital, Irbil, or to minority populations, said deputy national security adviser Ben Rhodes.

Laser-guided bombs

The first strike involved 500-pound laser-guided bombs on a "mobile artillery piece" used by ISIS at about 6:45 a.m. ET Friday, Pentagon spokesman Rear Adm. John Kirby said.

It came in response to an ISIS advance this week on what officials call U.S. interests in Iraq's Kurdish region in the north. The militants took towns from the Kurdish Peshmerga.

Before the onslaught, the region had been the most stable in Iraq and a cooperative ally of the United States. U.S. military advisers and consular personnel are stationed in Irbil.

The mobile artillery battery hit Friday was based outside Irbil, Kirby said.

In announcing his airstrike decision Thursday night, Obama said the militants would get hit "should they move towards the city."