U.S. has armed drones over Baghdad, official says

Armed drones. Mass graves. The Iraq crisis escalated Friday, CNN reports. 

A U.S. official confirmed to CNN that armed American drones started flying over Baghdad in the previous 24 hours to provide additional protection for 180 U.S. military advisers in the area. Until now, U.S. officials had said all drone reconnaissance flights over Iraq were unarmed.

Using the drones for any offensive strikes against insurgent Islamic State in Iraq and Syria fighters would continue to require approval from U.S. President Barack Obama.

The news came on the same day that Human Rights Watch said two mass graves believed to contain the bodies of Iraqi soldiers, police and civilians killed by the Sunni ISIS fighters and their militant allies have been discovered in Saddam Hussein's hometown of Tikrit.

Claims of atrocities by both sides have increased as the conflict widens in Iraq.

Earlier Friday, Amnesty International released a report saying it has evidence pointing to a pattern of "extrajudicial executions" of Sunni detainees by government forces and Shiite militias in the northern Iraqi cities of Tal Afar, Mosul and Baquba.

"Reports of multiple incidents where Sunni detainees have been killed in cold blood while in the custody of Iraqi forces are deeply alarming," said Donatella Rovera, Amnesty International's senior crisis response adviser, who is currently in northern Iraq. "The killings suggest a worrying pattern of reprisal attacks against Sunnis in retaliation for ISIS gains."

Meanwhile, witnesses said gunmen shot down an Iraqi military helicopter with an anti-aircraft weapon placed on a truck near Salaheddin University in Tikrit, about 160 kilometers (100 miles) north of Baghdad. The Iraqi Defense Ministry denied the helicopter was shot down.