The National Security Agency has been working closely with the CIA when it comes to targeted drone strikes against terrorists abroad.
The revelation comes from the Washington Post's latest review of documents leaked by former NSA contractor Edward Snowden, who is still taking asylum in Russia.
Those documents include an email from the widow of Hassan Ghul, who was a close associate of Osama bin Laden.
The email provided clues of Ghul's whereabouts, which may have led to the drone strike that killed him last October in Pakistan. According to the Post, the United States has never publicly acknowledged targeting him.