Drone attacks in Pakistan and Yemen against alleged terrorists have killed innocent civilians instead and may amount to war crimes, according to two human rights groups that released reports today.

Human Rights Watch issued a 97-page report Tuesday that examines six incidents, most using armed drones, from 2009 to 2013. At least 57 civilians died because of the strikes, which killed 82 people.

"The U.S. says it is taking all possible precautions during targeted killings, but it has unlawfully killed civilians and struck questionable military targets in Yemen," said Letta Tayler, who works for the organization and wrote the Between a Drone and Al-Qaeda: The Civilian Cost of U.S. Targeted Killings in Yemen report.

Human Rights Watch researchers spent six weeks in the country interviewing nearly 100 people, including witnesses and relatives, about the strikes.

"Yemenis told us that these strikes make them fear the U.S. as much as they fear Al-Qaeda in the Arabian Peninsula," said Tayler. ............