The alleged mastermind of the 9/11 attacks and four of his alleged co-conspirators "would be on death row as we speak" if politics hadn't blocked U.S. Attorney General Eric Holder from prosecuting the five men in a civilian court, the nation's top law enforcement official said today, four years after he announced his ill-fated decision in the case.

The case is now being prosecuted by the U.S. military at Guantanamo Bay, Cuba, where prosecutors and defense attorneys have been haggling for more than a year over pretrial arrangements. It's unclear when the trial will get underway.

"I think that what we have seen over these past four years - not to be egocentric about this - but that I was right," Holder told reporters today. "And I think that the facts and events that have occurred since then demonstrate that."

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In responding to a question from ABC News, Holder was unequivocal in defending his 2009 decision as "the right one." He took aim at criticisms lodged at his decision, including heat he took from Democrats such as Sen. Chuck Schumer of New York.

"I think that had we gone along the path that I announced at that time, we would not have had to close down half of Manhattan, it wouldn't have cost $200 million a year, and the defendants would be on death row as we speak," Holder said, speaking at an unrelated news conference. "We unfortunately did not go down that road. … The opposition was largely political in nature. And I think this is an example of what happens when politics gets into matters that ought to be simply decided by lawyers and by national security experts."

Holder has never wavered in believing he made the right choice from the start. He scolded naysaying lawmakers in April 2011 for what he saw as their overreach.

"Do I know better than them? Yes," Holder said at the time. "I respect their ability to disagree but they should respect that this is an executive branch function, a unique executive branch function."

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Two days after President Obama took office in 2009, the new commander-in-chief signed an executive order calling for the closure of the detention facility at Guantanamo Bay. As part of that effort, Holder and his Justice Department were to lead a review of the detainees and determine which ones could be released or prosecuted.

At a news conference in Washington Nov. 13, 2009, Holder announced his determination in the case of Khalid Sheikh Mohammed and others: "After eight years of delay, those allegedly responsible for the attacks of September the 11th will finally face justice. … They will be brought to New York to answer for their alleged crimes in a courthouse just blocks away from where the Twin Towers once stood."

But within months, under heavy pressure from New York officials, Republican lawmakers and even the White House, Holder reversed course, halting the planned proceedings in New York and ultimately deciding to send the case to the military for prosecution at Guantanamo Bay.

"[We] were prepared to bring a powerful case against Khalid Sheikh Mohammed and his four co-conspirators - one of the most well-researched and documented cases I have ever seen in my decades of experience as a prosecutor," Holder said at a news conference in April 2011.

"Sadly, this case has been marked by needless controversy since the beginning. But despite all the argument and debate it has engendered, the prosecution of Khalid Sheikh Mohammed and his co-conspirators should never have been about settling ideological arguments or scoring political points. … It is my sincere hope that, through the actions we take today, we will finally be able to deliver the justice [that victims] have so long deserved."