> ## Content Index > Fetch the complete content index at: https://www.vitalcitynyc.org/llms.txt > Use this file to discover other available public pages before exploring further. # The Terrorist Threat, Then and Now - URL: https://www.vitalcitynyc.org/nyc-terrorist-threat-before-and-after-9-11/ - Published: 2026-09-05T16:00:13.000Z - Updated: 2026-09-05T16:00:12.000Z - Description: New York City is under a different type of risk, but danger still looms large. - Author: Michael Chertoff - Tags: #911-anniversary-issue, 9/11, Looking Back, Looking Forward, #september-11-25th-anniversary-remembrance On the morning of September 11, 2001, the threat to this country materialized as hijacked commercial airliners used as kinetic weapons. In New York, 2,753 people were killed. It was the single deadliest terrorist attack in history, and it happened in the heart of America’s largest city, on a clear Tuesday morning. U.S. law enforcement and the intelligence community have spent much of the quarter century since that day implementing measures to keep it from happening again. The work is continuous, because the threat keeps evolving and our defenses are always adapting. By the time one of us became secretary of homeland security in 2005, the institutions meant to prevent the next attack were still taking shape, and many of the hardest questions were still unanswered. Before 9/11, we organized American security around foreign threats and largely through the Defense Department. When the Berlin Wall fell, it felt like the end of an era and a time when great dangers were lessening. The attacks made clear that threats weren’t lessening, only morphing: They were now from networks that opposed our way of life and could reach symbols of American freedom on a clear Tuesday morning. When the new millennium dawned, the homeland felt secure. After that day, it did not. ### A coordinated response The post-9/11 response reshaped how our country defends itself. The Bush administration created the Department of Homeland Security to unify the fragmented security apparatus and to break down the silos between federal agencies that weren’t built for information sharing. The guiding principle was unity of effort, and a single line of sight across the agencies responsible for securing America. For most Americans, visible changes arrived first in airports. Aviation security and the entire experience of flying were reimagined and federalized. That made sense, because it was airplanes that had been converted into missiles on that darkest day. New York City correctly adopted extensive measures. The city turned the NYPD into a counterterrorism force with an intelligence division that posted detectives in cities overseas and a Domain Awareness System that drew cameras, license plate readers and sensors into a single picture. The Lower Manhattan financial district was hardened with bollards, checkpoints and surveillance. Taken together, these measures have made the city far harder to attack at scale than it was on September 11, 2001\. The progress made should not be lost; it’s not an accident that the country and the city haven’t suffered another mass-casualty attack in a quarter century. ### The threat changed shape And yet the threat has continued to evolve. It changed shape, and the most important adaptation is a challenge to detect. We’ve moved from large terrorist organizations to lone-wolf operators, radicalized individuals intent on maiming and killing just the same. In 2001, a complex, coordinated attack required years of physical sanctuary, face-to-face vetting and structured training camps. Money moved, people traveled, conversations were intercepted. The very scale that made al-Qaida dangerous also gave us the surface area to find it. The lone attacker provides a fraction of that trail. The sharpest evolution is the asymmetric attack enabled by technology. The 9/11 plot demanded a mastermind, the planning of a Khalid Sheikh Mohammed and the reach of an Osama bin Laden. Today a person can self-radicalize online in a matter of weeks and carry out an attack of real impact with no organization behind him, no handler and no border to cross. The plotting phase is now stripped down to a single individual, which is far harder to see coming. New Yorkers have witnessed this progression firsthand. The 2009 plot to bomb the subway, directed by al-Qaida from a location in Pakistan, was an organized conspiracy our defenses were designed to catch, and we caught it. The attacks that followed were smaller and more self-directed: the 2016 Chelsea bombing, the 2017 pipe bomb at the Port Authority and the 2017 truck attack on the West Side Highway that killed eight, the deadliest terrorist attack in the city since 9/11\. Each required less organization than the last and each was harder to see coming. The cast of adversaries has widened as well. Back then it was individuals motivated by a distorted, radical reading of Sunni Islam who were the chief threat. In recent years, Iran has repeatedly sought to assassinate former U.S. government officials and Iranian dissidents on American soil, increasingly working through criminal networks to distance the plots from its intelligence service and to evade the FBI. Violent domestic extremism has become a category of its own, with dedicated prevention units and threat assessment teams. The most concerning plots no longer fit a single profile. Concealing plans for working plots has also gotten easier. The operational milestones of modern plots are increasingly shielded by technology. From pre-attack surveillance conducted through open-source satellite imagery to coordination over encrypted messaging apps, the digital footprint of a conspiracy has become far harder to trace. The windows that law enforcement and the intelligence community once relied on to interrupt an attack have narrowed. At the same time, the battle lines are no longer divided between the digital and the tangible. Modern adversaries seek a dangerous convergence, using cyber exploits to disable physical security systems, manipulate air traffic control data or disrupt critical infrastructure like power grids. A well-timed ransomware or operational technology attack could blind first responders or paralyze defenses at the very moment a kinetic or drone incident begins. Drones are the clearest point of convergence. Twenty-five years ago, the weapon was a passenger jet, and today the airspace faces a decentralized threat from commercial drones, the unmanned aircraft systems whose range and payload grow cheaper and more capable every year. These systems have proven themselves in Ukraine and the Middle East, and the danger reaches well beyond aviation, to the parades, festivals and sporting events at the center of community life. In 2022 outside Chicago, a sniper on a rooftop opened fire on the crowd gathered along the route for Highland Park’s Fourth of July parade. What he reached from a rooftop, a drone could now reach from the air. Looking ahead, artificial intelligence is the development to watch most closely, because it cuts both ways. It lowers the barrier to sophisticated cyberattacks and to disinformation convincing enough to move a market or start a panic. Indeed, an attack that could use AI to shut down hospitals, petroleum pipelines or banks would be a new form of terrorism, one that spreads fear without a single explosion. The very same tools will also help us defend, sharpening detection and speeding decisions under pressure, but they will not replace human judgment. The most difficult calls must involve a human in the loop. ### Vigilance and remembrance The question, 25 years on, is what the next generation of homeland defenders and public safety officials will do about it. They must keep adapting, because the adversary does. Detection must shift from finding networks to recognizing individuals before they act, which is far harder and leans on families, schools, clergy, mental health professionals and online platforms as much as on any intelligence agency. We must defend the seams where cyber and physical meet. And we must protect the open gatherings that make city life worth living without being overly intrusive. Two things have not changed in 25 years. The first is the dedication of the law enforcement officers, intelligence professionals and analysts across the intelligence community, DHS, DOJ, DOD and local agencies who work to protect this country. We have seen their dedication up close. It does not waver. The second is the aim of our adversaries, even as the adversaries themselves have changed. The target profile remains a deliberate mix of private sector and government entities, chosen to exploit vulnerabilities, instill widespread fear and inflict maximum harm. We will always be reminded that the human cost of 9/11 has not ended. Twenty-five years later, we continue to lose first responders to cancers and illnesses that trace to their exposure during the response and recovery operations at the World Trade Center, the Pentagon and Shanksville, Pennsylvania. The men and women who ran toward the danger in 2001, and who returned to the wreckage in the weeks and months that followed, are still paying a price for their service. The responders are not the only ones still falling ill. The office workers, residents and passersby who survived the towers, breathing the same toxic air as they fled Lower Manhattan, have in the years since developed the same diseases. The toll of September 11 is measured not only in the lives taken that morning, but in the lives quietly shortened among those who rushed in and those who barely got out. New York will mark the 25th anniversary of September 11 as both an ongoing target and a symbol of endurance. The city is far safer against the complex plots that defined 2001, and the harder task now is to see the less sophisticated attacks on the horizon: the lone figure radicalized in the privacy of their home, the inexpensive drone over a crowd, the line of code that opens a backdoor and the artificial intelligence that makes each one easier to plot and harder to see. That is a more difficult kind of vigilance, and recognizing it is how we must continue to adapt.