Asked Tuesday about the definition of "imminent threat" at a news conference on an unrelated topic, Holder said that "so many of these things are fact-based" and that "you can't examine the terms without reference to the facts." He said such details can be discussed only in a classified setting.
"Our primary concern is to keep the American people safe, but do so in a way that is consistent with our law and our values," Holder said.
The Justice memo says that delaying action against U.S. citizens who are linked to al-Qaida would create an unacceptably high risk because some al-Qaida leaders are continually plotting attacks on the U.S. and the U.S. may not always be aware of each specific plot as they develop.
This week, a bipartisan group of 11 senators asked President Barack Obama for all legal opinions underlying the authority to kill American citizens. The newly disclosed Justice Department document, first reported by NBC News on Monday night, represents an unclassified summary of those legal opinions and may have been prepared to deflect demands to see the actual classified legal opinions.
Sen. Dianne Feinstein, D-Calif., chairman of the Senate Intelligence Committee, said Tuesday that her panel received the unclassified document, and others, from the administration in June 2012 on a confidential basis. She said this document, coupled with other documents and closed briefings, "has allowed the Intelligence Committee to conduct appropriate and probing oversight into the use of lethal force."
Noting that she had been calling for public release of the legal basis for using lethal force, particularly against U.S. citizens, for more than a year, Feinstein said with disclosure of the white paper "the American people can review and judge the legality of these operations."