Holder: Drone strikes have killed four Americans

Since 2009, four American citizens have been killed oversas by counterterrorism drones, CNN reported.

On Wednesday, Attorney General Eric Holder wrote a letter to Senate Judiciary Committee Chairman Patrick Leahy detailing how the U.S. killed an American who was a senior operational leader of al-Qaida. He was targeted after allegedly plotting attacks against the U.S.

The administration also acknowledged that three other Americans "have been killed by U.S. counterterrorism operations outside of areas of active hostilities." These individuals were not specifically targetted, but all the drone strikes were justified to protect the United States from danger, Holder wrote.

While drone-strike deaths had been reported, this is the first time the administration has confirmed the deaths were part of a counterterrorism effort.

The announcement comes just a day before President Obama is set to speak on policies that would change how drones are used.

On Thursday, President Obama is expected to restrict the use of unmanned drone strikes, according to the New York Times. He also plans to shift control of drones away from the C.I.A. and instead to the military.

This will be President Obama's first major counterterrorism speech this term. Overall drone use will decrease, as the policy contains stricter standards.

Foreign nationals will be treated the same as U.S. citizens: Only targets that pose a "continuing, imminent threat to Americans" will be considered, which would exclude threats to other countries without a direct tie to the U.S.

It will also limit strikes on the unknown -- the current policy allows "signature strikes" on men assumed to be part of al-Qaida or another enemy group. The strikes have been criticized for needlessly killing civilians.

Obama will speak Thursday at the National Defense University, where he will also outline his plans for the closure of Guantanamo Bay.