Updated

The nation's top law enforcement official Wednesday tried to dismiss questions over whether Sunday's killing of Usama bin Laden was legal, saying in no uncertain terms he is "proud" of the assault and it "was justified as an act of national self defense."

"Let me make something very clear," Holder told the Senate Judiciary Committee. "The operation in which Usama bin Laden was killed was lawful. He was the head of al Qaeda, the organization that had conducted the attacks of September 11th. He admitted his involvement ... [and] he said he would not be taken alive."

Holder said it's lawful to "target an enemy commander in the field," just as U.S. forces did during World War II when it shot down a plane carrying Japanese Adm. Isoroku Yamamoto.

Bin Laden was "by my estimation, and the estimation of the Justice Department, a lawful military target, and the operation was conducted consistent with our law [and] with our values."

Bin Laden made no attempts to surrender and there was "no indication he wanted to do that," Holder said. Even if the Al Qaeda leader had surrendered, there would have been a "good basis" for "those very brave Navy SEALs" to shoot bin Laden "in order to protect themselves and the other people who were in that building," including "substantial numbers of women and children" who were not harmed in the raid.

Both Democrats and Republicans on the Senate Judiciary Committee supported Holder's assessment, with Sen. Lindsey Graham, R-S.C., saying the Navy SEALS who killed bin Laden "had to believe the moment they encountered bin Laden -- whether he raised his hands or not -- that could be a fake surrender."

"They were well within their rights in shooting him as soon as possible," Graham said.

Holder was not with President Barack Obama, Secretary of State Hillary Clinton and other administration officials as they monitored events from the White House Situation Room on Sunday. A Justice Department spokesman did not return emails seeking comment or explanation.

Also at Wednesday's hearing, Holder said he has "serious concerns" that bin Laden's death could inspire attempts of retaliation.

Earlier this week, he held a conference call with U.S. Attorneys from across the nation, outlining additional steps they should take and "making sure that they ... were on their toes."

"This is a difficult time for this nation after the death of bin Laden," Holder said Wednesday. "We will ultimately be more safe as a result of his death, but in the short-term I think we have some serious concerns that we have to be ready to address."

Holder said more names will "probably" be added to the nation's terrorism watch-lists, particularly the no-fly list, after authorities "glean information" from material seized inside bin Laden's compound in Pakistan. In addition, Holder suggested the number of overseas wiretap requests by the Justice Department is likely to rise from the new information.