The Obama administration says between 64 and 116 civilians have been killed by drone and other U.S. strikes in Pakistan, Yemen and Africa since President Barack Obama took office in 2009.
Friday's disclosure was the administration's first public assessment of the number of civilians killed in these types of operations. Some human rights advocates say the number is significantly higher.
Obama also signed an executive order that makes protecting civilians a central element in planning U.S. military operations.
While sketchy details often emerge about individual drone strikes, the full scope of the U.S. drone program has long been shrouded from view. It is a key tool of Obama's counterterrorism strategy.
The civilian casualties disclosed do not reflect U.S. air attacks in Afghanistan, Iraq or Syria.