Twenty-five years after September 11, 2001, there is a lesson from that terrible morning that America and its allies cannot afford to forget: deterrence fails when an adversary becomes convinced we lack the resolve to respond forcefully.
Osama bin Laden made precisely that mistake.
During the 1990s, he watched the United States closely. He saw American forces withdraw from Somalia after the bloody fighting in Mogadishu. He watched the response to attacks against Americans in Saudi Arabia, including the 1996 bombing of the Khobar Towers.
Al-Qaeda had already demonstrated both intent and growing ambition: the first attack on the World Trade Center in 1993, the bombings of the American embassies in Kenya and Tanzania in 1998, and the attack on the USS Cole in October 2000, which killed 17 American sailors. Their determination never wavered.
Bin Laden drew a catastrophic conclusion from these events: America was powerful but weak-willed. Kill enough Americans, he believed, and America might retreat entirely from its commitments in the Middle East, and elsewhere.
He and many in Al-Qaeda claimed to be galvanized by U.S. policy in the region, and for Bin Laden himself, by the presence of the U.S. military on Saudi soil, the country that hosts Islam’s holy sites. This was the basis of his claimed declaration of war against the U.S.
Bin Laden’s miscalculation, misperceiving the U.S. as weak and susceptible to fear, helped set the stage for September 11. But our policies also contributed to that perception, and they may unfortunately be doing the same today with different adversaries.
A gigantic gamble
By late 1999, bin Laden and his lieutenants had already embraced Khalid Sheik Mohammed's audacious proposal for what they called the "Planes Operation." KSM's original concept was even larger than the attack ultimately carried out.
They were so sure America would not respond strongly that they had envisioned a possible “second wave” of attacks. Bin Laden and KSM became obsessed with striking spectacular symbols of American power: the Pentagon, the White House or Capitol, and, most importantly for them, bringing down the World Trade Center.
September 11 was more than a terrorist attack. It was a gigantic gamble
September 11 was therefore more than a terrorist attack. It was a gigantic gamble based partly on an assessment of American resolve. Bin Laden got that assessment terribly wrong.
Rather than frightening the United States into retreat, al-Qaeda awakened the country. In Franklin Roosevelt's words after Pearl Harbor, America responded in its "righteous might."
A generation of CIA officers later served in Afghanistan alongside our military brothers and sisters, and with our allies. Whatever judgments historians ultimately render about the wars that followed – and particularly about decisions made years later – the immediate necessity after September 11 was clear. We could not allow al-Qaeda to murder nearly 3,000 people on American soil and then remain protected in its Afghan sanctuary.
Lessons for tomorrow
Today, however, the most important lesson of September 11 may be the lesson that preceded it.
Our adversaries are always watching us. They are probing. They are measuring our responses. And they are concluding what we do – and what we fail to do.
That matters enormously as Russia escalates its hybrid war against the West.
Europe has already witnessed sabotage, cyberattacks, incendiary devices, attacks on infrastructure and increasingly brazen operations using proxies and expendable recruits.
In 2024, incendiary parcels moved through European logistics networks, including one that ignited at a DHL facility at Leipzig/Halle Airport.
German officials said only a delay kept the device from potentially detonating aboard an aircraft. Russia would return to that same airport, not unlike how Al-Qaeda returned to the World Trade Center as a target.
Intelligence services study what works
This August, an explosives-laden drone was discovered near a Ukrainian cargo aircraft at that same airport. Germany has now publicly blamed Russia for the attempted attack. Two other drones were also discovered. These operations should trouble us for reasons extending far beyond Leipzig.
They show our Russian intelligence adversaries (principally in this case the GRU and FSB) experimenting, testing our resolve, and showing determination.
Intelligence services study what works. They test security systems, recruitment mechanisms, delivery methods, and political reactions. An operation that fails today may provide lessons for an operation that succeeds tomorrow.
We learned that on September 11.
Today’s foothold, tomorrow’s weapon
Russia and China are conducting similar reconnaissance in another domain: cyberspace. Russian state intelligence actors and proxies have penetrated or targeted Western energy and other critical-infrastructure networks.
Chinese state-sponsored hackers and proxies have similarly established persistent access inside American communications, energy, transportation, and water and wastewater infrastructure.
Why obtain such access?
Because in a future crisis, today's intelligence foothold can become tomorrow's weapon. Turn off critical systems during a national emergency in the United States; or, potentially, create that very national disaster at a time of their choosing to suit their strategic aims.
We failed to fully appreciate how imaginative, patient, and ambitious the enemy had become. Today, we risk making the same conceptual mistake with hybrid warfare
The parallel with the years before September 11 is not that Vladimir Putin or Xi Jinping is Osama bin Laden. They are obviously very different adversaries with vastly different capabilities, objectives, and calculations.
But the parallel is our own vulnerability to complacency.
Before September 11, Jihadist terrorism was a recognized threat. The warning signs existed. Attacks had already occurred. Yet we failed to fully appreciate how imaginative, patient, and ambitious the enemy had become.
Today, we risk making the same conceptual mistake with hybrid warfare. Because an incendiary parcel, cyber intrusion, severed undersea cable, or drone incident does not look like columns of tanks crossing a NATO frontier, we too often treat each as an isolated event rather than as part of an escalating campaign.
Moscow is watching how we respond. Beijing is watching too.
If Russia concludes that it can intimidate Ukraine, sabotage European infrastructure and steadily probe NATO without paying a meaningful price, why should we expect it to become less aggressive?
And if China watches Western democracies fracture under pressure, what conclusions will Beijing draw about our willingness to defend Taiwan?
Capability without resolve
Deterrence ultimately exists inside the mind of an adversary. Military capability matters enormously. But capability without demonstrated resolve can invite the very confrontation it is intended to prevent.
Twenty-five years after September 11, that may be one of its most important lessons.
Our enemies are still watching. They are still probing for weakness
Our enemies are still watching. They are still probing for weakness. They are still searching for imaginative and sensational ways to frighten our societies and divide our democracies.
Our resolve must match their creativity, and our unity must be stronger than their determination to destroy it.
Sean Wiswesser is a former CIA Senior Operations Officer and expert on Russian Intelligence, Espionage, and Defense Issues.
