By Joseph S. Nye Jr., Dean Emeritus, Harvard University’s John F. Kennedy School of Government 

The terrorist attacks of September 11, 2001, were a horrific shock. Images of trapped victims leaping from the Twin Towers are indelible, and the intrusive security measures introduced in the wake of the attacks have long since become a fact of life.

But skeptics doubt that it marked a turning point in history. They note that the immediate physical damage was far from fatal to American power. It is estimated that the United States’ GDP growth dropped by three percentage points in 2001, and insurance claims for damages eventually totaled over $40 billion – a small fraction of what was then a $10 trillion economy. And the nearly 3,000 people killed in New York, Pennsylvania, and Washington, DC, when the al-Qaeda hijackers turned four aircraft into cruise missiles was a small fraction of US travel fatalities that year.

While accepting these facts, my guess is that future historians will regard 9/11 as a date as important as the Japanese attack on Pearl Harbor on December 7, 1941. The surprise attack on the US naval base in Hawaii killed some 2,400 American military personnel and destroyed or damaged 19 naval craft, including eight battleships. In both cases, however, the main effect was on public psychology.

For years, President Franklin D. Roosevelt had tried to alert Americans to the Axis threat but had failed to overcome isolationism. All that changed with Pearl Harbor. In the 2000 presidential election, George W. Bush advocated a humble foreign policy and warned against the temptations of nation-building. After the shock of 9/11, he declared a “global war on terror” and invaded both Afghanistan and Iraq. Given the proclivities of top members of his administration, some say a clash with Iraq’s then-dictator, Saddam Hussein, was predictable in any case, but not its manner or cost.

What 9/11 illustrates is that terrorism is about psychology, not damage. Terrorism is like theatre. With their powerful military, Americans believe that “shock and awe” comes from massive bombardment. For terrorists, shock and awe comes from the drama more than the number of deaths caused by their attacks. Poisons might kill more people, but explosions get the visuals. The constant replay of the falling Twin Towers on the world’s television sets was Osama bin Laden’s coup.

Terrorism can also be compared to jujitsu, in which a weak adversary turns the power of a larger player against itself. While the 9/11 attacks killed several thousand Americans, the “endless wars” that the US subsequently launched killed many more. Indeed, the damage done by al-Qaeda pales in comparison to the damage America did to itself.

By some estimates, nearly 15,000 US military personnel and contractors were killed in the wars that followed 9/11, and the economic cost exceeded $6 trillion. Add to this the number of foreign civilians killed and refugees created, and the costs grow even more enormous. The opportunity costs were also large. When President Barack Obama tried to pivot to Asia – the fastest-growing part of the world economy – the legacy of the global war on terror kept the US mired in the Middle East.

Despite these costs, some say that the US achieved its goal: There has not been another major terrorist attack on the US homeland on the scale of 9/11. Bin Laden and many of his top lieutenants were killed, and Saddam Hussein was removed (though his connection to 9/11 was always dubious). Alternatively, a case can be made that bin Laden succeeded, particularly if we consider that his beliefs included the value of religious martyrdom. The jihadist movement is fragmented, but it has spread to more countries, and the Taliban have returned to power in Afghanistan – ironically, just before the 9/11 anniversary that President Joe Biden originally set as the target date for withdrawing US troops.

It is too early to assess the long-term effects of the US withdrawal from Afghanistan. The short-term effects of the chaotic exit are costly, but in the long term, Biden may come to be seen as correct to forswear the effort at nation-building in a country divided by mountains and tribes and united mainly by opposition to foreigners.

Leaving Afghanistan will allow Biden to focus on his grand strategy of balancing the rise of China. For all the damage done to US soft power by the chaotic manner of the exit from Afghanistan, Asia has its own longstanding balance of power in which countries like Japan, India, and Vietnam do not wish to be dominated by China and welcome an American presence. When one considers that within 20 years of America’s traumatic exit from Vietnam, the US was welcome in that country as well as the region, Biden’s overall strategy makes sense.

At the same time, 20 years after 9/11, the problem of terrorism remains, and terrorists may feel emboldened to try again. If so, the task for US leaders is to develop an effective counter-terrorism strategy. Its core must be to avoid falling into terrorists’ trap by doing great damage to ourselves. Leaders must plan to manage the psychological shocks at home and abroad.

Imagine what the world would be like if Bush had avoided the tempting rallying cry of a global war on terror and responded to 9/11 by carefully selected military strikes combined with good intelligence and diplomacy. Or, if he had gone into Afghanistan, imagine that he had withdrawn after six months, even if that had involved negotiating with the despised Taliban.

Looking forward, when the next terrorist attacks come, will presidents be able to channel public demand for revenge by precise targeting, explaining the trap that terrorists set, and focusing on creating resilience in US responses? That is the question Americans should be asking, and that their leaders should be addressing.

Joseph S. Nye, Jr. is Dean Emeritus of Harvard University’s John F. Kennedy School of Government 

©Project Syndicate 2021