Appearing before a Senate Judiciary Committee oversight hearing that at times grew testy during questioning by Republican members, Holder said there is no exact time frame for closing the Guantanamo Bay, Cuba, prison.
Sen. Jeff Sessions, R-Ala., used his opening statement to express his displeasure with Holder and the Obama administration regarding plans to shut down Gitmo and move some detainees to a facility in the United States, and to try some defendants in civilian courts. Those actions, he said, "have shaken my confidence in your leadership."
Holder defended the use of civilian courts to try terror suspects, as the administration of George W. Bush had done, along with military courts.
"Instead of pursuing a narrow approach to fighting terrorism, we have to be flexible, we have to pragmatic and we have to be aggressive," he said.
On the decision about where to try the 9/11 suspects, including Khalid Sheik Mohammed, Holder called it "a very close call."
"It should be clear to everyone by now that there are many legal national security and practical factors that have to be considered here," he said.
Asked by Sen. Herb Kohl, D-Wis., for a timeline for closing Gitmo, Holder replied it won't happen until Congress appropriates money to convert the Thomson prison facility in Illinois to house the Gitmo prisoners.
Asked by Kohl when a decision will be announced concerning where the 9/11 plotters will be tried, Holder answered "New York is not off the table" and a decision is still "a number of weeks" away.
Sessions and Holder later went back and forth over the issue of trying 9/11 plotters in civilian courts in New York and the senator said he thinks the attorney general should "re-evaluate" the situation.
"I don't think the people of New York want this trial anywhere in their state or their city ...," Sessions said.
Holder responded that "these decisions on a case-by-case basis with the aim of being most effective in a particular trial, and protecting the American people."
Sen. Charles Grassley, R-Iowa, sought to get Holder to give the committee the list of attorneys in his department who had previously represented terror detainees. Those names have been reported in the media.
Holder said he would not because "there has been an attempt to take the names of the people who represented Guantanamo detainees and to drag their reputations through the mud."
Notable deaths of 2014 [PHOTOS]