On the morning of Sept. 11, 2001, Secretary of Defense Donald Rumsfeld arrived at the Pentagon and, as he did every morning, reviewed policy at a small, round wooden table once used by Gen. William Tecumseh Sherman, the legendary Union leader. It was going to be a busy day, full of meetings with House members, haggling over the defense budget.

He started with a working breakfast; a few minutes after his guest departed, Rumsfeld was informed by an aide that an airplane had crashed into one of the World Trade Center’s twin towers. Assuming it was a tragic accident, he flipped on the television but put it on mute, and turned back to his papers. A senior intelligence official then entered Rumsfeld’s office and briefed him on various global hotspots. There was no inkling, for the moment, that what had happened at the World Trade Center was of cataclysmic importance.

As the official spoke, Rumsfeld could hear the faint hum of low-flying commercial airliners cruising toward Washington’s Reagan National Airport. He heard the noise most days, since planes often took routes over the Potomac River, close to the Pentagon. He thought nothing of it, but then his eyes happened to turn toward the television screen. He saw the second tower engulfed in flames. Stunned, he cut the briefing short.

Rumsfeld called in advisers, and they huddled around his table. They made calls, reviewed press reports. As they discussed the unfolding scene in lower Manhattan, Rumsfeld felt the floor rumble. For the Pentagon, a sprawling concrete castle, to shake was disconcerting. As he recounts in his memoir, Known and Unknown, Rumsfeld leaped to his feet and hustled down the E Ring, the Pentagon’s outer corridor, only to be confronted by heavy smoke.

He went outside and saw that clouds of black smoke were rising from the west side of the Pentagon. He was informed that a plane had crashed into the building. Moving across the grass, he picked up a twisted piece of metal debris. He rushed toward the smoke, where Pentagon employees were scrambling to help the wounded. Firemen and emergency medical personnel had yet to arrive, and the fiery gash was widening by the minute.

It was chaos, Rumsfeld recalls in a conversation with National Review Online. But ten years later, he says, it is the response to the crisis, not the details of that day, that reveals the most about the character of the American people and the policies of the Bush administration. “As I look back, it is amazing to me that we’ve managed to get through ten years without another successful attack on the United States,” he says. “That didn’t just happen.”

Rumsfeld notes that the anniversary of the horror should, of course, be a time to reflect on lives lost. Rumsfeld, for his part, will be at the Pentagon, participating in a memorial service for those killed there that morning. But he also adamantly believes that, ten years later, Americans, and especially our lawmakers, should carefully review the military and intelligence lessons learned.

Going ten years without another successful attack is a blessing, Rumsfeld says, but he cautions that it guarantees nothing in coming years. Continued vigilance is needed. “The coordination and cooperation of the coalition of over 90 countries that have been sharing intelligence, tracking bank accounts, and participating in the effort that President Bush led, to try to put pressure on terrorists everywhere in the world, is the reason, I think, that we’ve been successful,” he says.

“The decision to go after them, to make everything they do more difficult, has worked. It has made it harder for them to communicate with each other, harder to travel, harder to raise money, harder to recruit,” Rumsfeld asserts. “That has been beneficial. I think the structures that the Bush administration put in place – Guantanamo Bay, indefinite detentions, the Patriot Act, the military commissions — those things have contributed to that.”

Rumsfeld is struck by how President Obama, who famously railed against the Bush administration’s intelligence tactics, continues to implement Bush-era anti-terror policies, perhaps cognizant of how important those post–September 11 programs are to national security. “To the credit of the Obama administration,” Rumsfeld says, “while they campaigned against all of those things, once in office, they decided to keep those structures in place to protect the American people.”

“That has been a good thing,” Rumsfeld says, and he points out that leaders of both parties are adapting to this century’s national-security challenges. Whereas in the Clinton years the military budget was reduced and combatting terrorism was not a prominent part of the U.S. military’s mission, Rumsfeld argues that the Bush administration and the Obama administration, though less assuredly, have clearly understood the necessity of addressing terrorism.

The change in approach has been a “distinctive one,” Rumsfeld says, a strong example of putting aside partisan differences in a shared commitment to defending against a looming threat. “Prior to the 9/11 attacks, the common way of treating terrorists was as criminals, as if they were bank robbers. We would indict them in absentia, and let it go at that,” Rumsfeld says. “That contributed, I would say, to the attacks on 9/11.”

A decade later, Rumsfeld hopes that Washington politicians will continue to focus on terrorism as one of the central security issues of our time, not shelving it, and the Bush administration’s programs, simply because of the passage of time. “What we are really engaged in here is a battle that is not going to be won with bullets, but with ideas over time,” he says. “We have to do a much better job of competing in the marketplace of ideas, offering an antidote to a culture in which people can be recruited, in these radical madrassas around the world, to strap on suicide vests.”

“We need people to stand up, Muslim and non-Muslim alike, condemning those kinds of actions,” Rumsfeld says. He urges President Obama, whom he applauds for certain things, to do more in this arena, taking on the radical Islamists. “We do not have good metrics on their success,” he laments. “We have to be concerned, attentive, and aware. The lethality of weapons today is of a different order. It might not be 3,000 people dead, but 300,000 people dead with a biological weapon, a chemical weapon, or a radiation weapon.”

Rumsfeld believes that we need to honor the victims of 9/11, but not in some gauzy, sentimental way. With the stakes as high today as they were ten years ago, this 79-year-old statesman is in no mood to mince words. “Our margin for error is so modest,” he says. “We have to be willing, as Americans, to look ahead and take the steps necessary to provide for the security of the American people and see that ‘the next time’ doesn’t happen.”

— Robert Costa is a political reporter for National Review.