Twenty-five years on, it’s still hard to grasp the significance of 9/11 because it remains a moving target. The repercussions rippling out of that terrible day never seem to stop—or even slow down.

The era of 9/11 began with one misbegotten U.S. war of choice in the Middle East, in Iraq. We are marking its 25th anniversary with another misbegotten U.S. war of choice in the Middle East, in Iran. In between, we’re not quite sure what we have learned, other than Americans never seem to get regime change right, whether we send in troops or not. And Washington still finds itself mired in a region that successive presidents have said they want to distance themselves from.

Twenty-five years on, it’s still hard to grasp the significance of 9/11 because it remains a moving target. The repercussions rippling out of that terrible day never seem to stop—or even slow down.

The era of 9/11 began with one misbegotten U.S. war of choice in the Middle East, in Iraq. We are marking its 25th anniversary with another misbegotten U.S. war of choice in the Middle East, in Iran. In between, we’re not quite sure what we have learned, other than Americans never seem to get regime change right, whether we send in troops or not. And Washington still finds itself mired in a region that successive presidents have said they want to distance themselves from.

The Middle East quagmire only seems to grow deeper, the march of U.S. folly more self-destructive. After the expenditure of trillions of dollars and hundreds of thousands of American and Iraqi lives and limbs, a U.S. Army study concluded that “the only victor” to come out of the 2003 Iraq war appeared to be “an emboldened and expansionist Iran.”

Now, in 2026, President Donald Trump’s latest war may have given Iran new advantages, at least for the moment. Though it has hit Tehran hard, the war has further weakened the U.S. role in the region while, once again, seriously draining its military firepower and piling on ever more debt. The prolonged conflict may also be reigniting the fading embers of al Qaeda.

Beyond that, the downstream effects of 9/11 in both political and geopolitical terms are still so far-reaching that scholars will likely be debating them for a long time.

How did a tiny, ragtag group of jihadists manage to provoke the world’s only superpower into a series of so-called forever wars—the post-9/11 global war on terror constitutes by far the longest war in U.S. history—that drained its power and prestige? What were the opportunity costs of this vast expenditure of blood and treasure over a quarter century—especially in terms of empowering China and, perhaps, encouraging Russia in its own bloody adventurism? As the military writer Elliot Ackerman has noted, “[W]hile Washington was repurposing the U.S. military to engage in massive counterinsurgency campaigns and precision counterterrorism operations, Beijing was busy building a military to fight and defeat a peer-level competitor.” Washington, suddenly alerted, is still trying to catch up to that strategic challenge after what one U.S. general described as the “era of the Great Distraction” following 9/11.

Some analysts have argued that the botched response to 9/11 also helped to upend domestic U.S. politics. Did the fumblings of the preceding Republican president, George W. Bush—especially his disastrous invasion of Iraq—so discredit the traditional party agenda that it opened the way to a reckless demagogue, Trump, who has since turned the Grand Old Party into his chew toy?

“Conservatism was never the same after the first improvised explosive device detonated in Baghdad,” Matthew Continetti wrote in his 2022 book, The Right: The Hundred-Year War for American Conservatism.

Then there’s the question of whether Americans really knew who they were fighting—if they ever mastered the “metrics” of the so-called war on terror, as Donald Rumsfeld, Bush’s hapless defense secretary, once put it.

Many strategic assessments conclude that, for all its costs, at least the war on terror prevented another large-scale attack on the U.S. homeland. But critical questions remain about how serious a threat that really was, and whether U.S. strategists mistook a marginal enemy—one that might have been quickly eliminated after 9/11—for an existential one.

U.S. President George W. Bush (center) calls for the creation of a national counterterrorism center during a press conference at the White House in Washington on Aug. 2, 2004. Stephen Jaffe/AFP via Getty Images

In his new book, All the Presidents’ Wars: Twenty-Five Years of America’s War on Terror, national security expert Peter Bergen takes the view that al Qaeda was a major strategic threat and the U.S. deserves credit for blunting it. Even so, Bergen eviscerates four different U.S. presidents and their administrations for badly mishandling that challenge.

Bergen, who famously produced the 1997 CNN interview in which Osama bin Laden declared war on the United States, writes that he is attempting a full history of what he says “is as much a consequential epoch in American life as the Cold War was” on some levels.

All the Presidents’ Wars: Twenty-Five Years of America’s War on Terror, Peter Bergen, W.W. Norton, 432 pp., $32.99, September 2026

He gets most of that history right. It’s all here in a tight 400 pages, the long, ugly, almost farcical saga we’ve become familiar with: the missed opportunity to kill or capture Osama bin Laden and destroy al Qaeda quickly at Tora Bora, perhaps ending the war on terror in mere months; the fraudulently justified diversion into Iraq; and how that mistake in turn facilitated the Taliban resurgence in Afghanistan.

Bergen recounts, in great detail, how the unnecessary invasion of Iraq—and the brutal U.S. occupation that ensued in the heart of the Arab world—dramatically inflated the number of jihadis Washington had to fight. This........

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