The Domestic Legacy of 9/11
Daniel Benjamin and Steven N. Simon
For years, America’s growing political dysfunction has largely been explained through economic and social forces: globalization, widening inequality, declining social mobility, the loss of industrial employment, and the economic disruption associated with China’s rise. These forces have undoubtedly contributed to polarization, distrust of institutions, hostility toward immigration, and the weakening of the American middle class.
But another major force has received far less attention: the war on terror.
The wars and counterterrorism campaigns launched after September 11, 2001, are usually judged by what happened overseas. Analysts count terrorist leaders killed, plots disrupted, intelligence failures exposed, and the enormous human and financial costs of Afghanistan and Iraq. Yet this conventional accounting misses another consequence: the way two decades of permanent security mobilization transformed American politics and institutions at home.
The direct costs were already immense. More than 7,000 American troops were killed in action and 53,000 wounded, while more than 30,000 service members and veterans took their own lives. Brown University’s Costs of War Project estimated that the post-9/11 conflicts added roughly $8 trillion to the national debt, with substantial future costs associated with veterans’ care.
But money and casualties tell only part of the story.
A Politics Built Around Fear
After 9/11, terrorism became more than a security problem. It became a powerful organizing force in American political life.
The possibility of another catastrophic attack encouraged a climate of permanent anxiety. Political leaders, media commentators and an expanding counterterrorism establishment repeatedly presented terrorism as an existential danger. Under these conditions, Americans became more willing to accept extraordinary government powers in exchange for security.
The result was not simply a stronger counterterrorism apparatus. The authors argue that the period contributed to declining social cohesion, weakening bipartisanship, growing xenophobia and anti-immigrant sentiment, and increasing distrust of political and foreign-policy elites.
Muslim Americans experienced this transformation particularly sharply.
President George W. Bush repeatedly insisted that the United States was fighting terrorism rather than Islam. Yet government policies and public rhetoric often sent a more complicated message. At least 1,200 Muslim men were detained after the attacks, many on immigration grounds, while law-enforcement agencies expanded scrutiny of Muslim communities. At the same time, influential public figures portrayed Islam itself as a threat.
The distinction between combating violent extremists and treating entire communities as potentially dangerous gradually became blurred.
And fear proved politically useful.
By the 2016 presidential election, Donald Trump was able to connect terrorism, Islam and immigration within a single political narrative. His rhetoric increasingly presented threats from abroad and perceived enemies within the United States as parts of the same problem. Once in office, this approach helped produce the travel restrictions targeting several Muslim-majority countries and reinforced a broader politics of suspicion toward immigrants and minorities.
From Foreign Enemies to Domestic Enemies
This may be one of the most consequential legacies of the post-9/11 era.
The war on terror accustomed American political culture to identifying dangerous individuals hidden within wider populations. Traditional warfare generally focuses on identifiable armies, governments and military installations. Counterterrorism works differently. It searches for individuals, networks, communications, financial transactions and patterns of behaviour before an attack takes place.
That required a new security infrastructure.
Federal agencies integrated intelligence, immigration, customs and law-enforcement databases. Joint terrorism task forces and intelligence-sharing centres expanded cooperation between national and local authorities. Systems originally created to detect terrorists gradually acquired broader public-safety and law-enforcement purposes.
The infrastructure was highly effective at collecting and connecting information.
But once such machinery exists, its purpose can change.
Tools designed to track terrorist networks can also identify protesters, immigrants, political activists and other groups. The authors point to the monitoring of protesters and journalists during demonstrations in Portland in 2020 as an example of how national-security capabilities could migrate into domestic political policing.
Technology has made this possibility even more significant. Large databases, commercial digital platforms and artificial intelligence allow governments to identify and monitor individuals on a scale that would previously have required enormous numbers of personnel.
The central democratic problem is therefore not merely whether these capabilities are useful. It is who controls them, against whom they are used, and what restraints prevent their political abuse.
The Growth of the Security State
The post-9/11 transformation was institutional as well as cultural.
The federal security bureaucracy expanded dramatically. Immigration enforcement grew in resources and personnel, while local police departments increasingly acquired military equipment. According to the authors, transfers of Defense Department equipment to local police increased enormously after 9/11, contributing to the militarization of domestic law enforcement.
The boundaries separating war, border security and domestic policing consequently became less distinct.
Military institutions also acquired larger homeland-security roles. The creation of the U.S. Northern Command after 9/11 strengthened military organization for homeland defense and support to civilian authorities. Later developments further reduced the institutional distance between military capabilities designed for conflict abroad and security missions at home.
None of this automatically produces authoritarian government. Democracies can possess strong intelligence agencies, capable armed forces and sophisticated law-enforcement systems while remaining democratic.
The danger arises when extraordinary powers become permanent and political leaders begin redefining political opponents as security threats.
The Expansion of Executive Power
The most important institutional legacy of the war on terror may therefore be the strengthening of the presidency.
American presidents had accumulated national-security authority long before September 11. But the attacks created political conditions in which extraordinary executive powers could expand rapidly. Surveillance, detention, secrecy, emergency authority and military force became easier to justify when presented as necessary to prevent another catastrophic attack.
George W. Bush constructed much of this post-9/11 architecture. Barack Obama modified parts of it but retained much of the system he inherited. Congress repeatedly authorized, accepted or failed to dismantle significant elements of it.
That created a structural problem.
A democratic system cannot safely depend indefinitely on the assumption that every future president will exercise extraordinary powers responsibly.
Powers created to confront genuine national-security threats remain available when a different president takes office. Institutions built to identify terrorists do not themselves determine who deserves to be classified as a threat. Political leaders ultimately influence those definitions.
This is where the post-9/11 legacy intersects with America’s contemporary democratic crisis.
The authors argue that Donald Trump inherited a government already equipped with powerful tools of surveillance, detention, immigration enforcement and emergency authority. The war on terror did not create authoritarian politics in the United States, but it made the institutional machinery available to a president willing to push executive authority much further.
The Enemy Moves Home
The transformation was psychological as well as institutional.
For much of the post-9/11 period, the terrorist was imagined as an external enemy who might secretly penetrate American society. Over time, however, the language used to describe external threats increasingly entered domestic politics.
Muslims were among the first communities subjected to this politics of suspicion. Later, similar language was directed toward immigrants. Eventually, protesters, cultural minorities and partisan opponents could also be described through a vocabulary of threat, invasion, extremism and internal enemies.
According to Benjamin and Simon, this represents one of the war on terror’s deepest political consequences: the idea of the “terrorist” gradually evolved from a description of a particular form of political violence into a broader model for imagining political opponents.
Once opponents cease to be viewed merely as citizens with different political beliefs and instead become existential threats, democratic compromise becomes much harder.
Politics begins to resemble war.
Veterans and Political Radicalization
Prolonged warfare can also reshape society through those who fight it.
The authors draw historical parallels with earlier periods when veterans carried military identities, organizational methods and political grievances back into civilian life. In contemporary America, some veterans of the Afghanistan and Iraq wars have joined militant political organizations such as the Oath Keepers and Three Percenters.
Members of such groups participated in the January 6 attack on the U.S. Capitol, with some employing military-style organization. The authors warn that the political radicalization of even a small portion of people with military or law-enforcement experience deserves serious attention.
Again, the argument is not that military service produces extremism. Rather, prolonged warfare can create political consequences when military experience, social polarization and narratives of national betrayal converge.
The International Costs Came Home
The war on terror also reshaped the international environment in ways that eventually affected American politics.
The invasion of Iraq removed Saddam Hussein and strengthened Iran’s regional position. The wars and instability of the broader Middle East contributed to displacement and migration. The rise of the Islamic State intensified terrorism fears in Europe and North America and strengthened populist political movements. Meanwhile, authoritarian governments could present themselves as indispensable partners against terrorism and receive international support despite their domestic repression.
The consequences of the war therefore did not remain confined to Afghanistan, Iraq or the wider Middle East. They circulated back into Western politics through migration, security policy, populism and growing public distrust of political establishments.
Twenty-Five Years Later
American commemorations of September 11 understandably focus on the people who died that day and those who sacrificed their lives afterward. There is also broad recognition that the Iraq war was a grave strategic mistake and that Afghanistan became a conflict lasting far longer than originally imagined.
But the domestic consequences of the response to 9/11 deserve equal scrutiny.
The United States spent two decades constructing institutions designed to identify threats before they could materialize. Surveillance expanded. Databases were integrated. Watch lists multiplied. Border enforcement became more militarized. Preventive policing became normalized. Executive secrecy and emergency powers increased.
These instruments were created because policymakers feared another September 11.
The democratic danger emerged when the definition of the enemy began to change.
A state powerful enough to find terrorists hidden inside society is also powerful enough to monitor immigrants, protesters and political movements. A presidency empowered to confront extraordinary national-security emergencies can use the same institutional inheritance for very different political purposes.
That does not mean that the United States should not have responded forcefully to al-Qaeda. Nor does it mean that every post-9/11 security measure was unnecessary. Intelligence cooperation and stronger law enforcement undoubtedly contributed to preventing attacks; the source itself acknowledges the improved effectiveness of American intelligence and law-enforcement institutions after September 11.
The larger lesson is about permanence.
Emergency powers rarely disappear simply because the emergency that created them has faded. Institutions acquire budgets, personnel, technology and political constituencies. Authorities granted for one purpose can eventually be used for another.
The war on terror therefore had two battlefields. One stretched from Afghanistan and Iraq to the wider campaign against jihadist organizations. The other developed quietly inside the United States—in its presidency, security institutions, policing practices and political culture.
The first war sought to protect American democracy from terrorism.
The enduring question is whether, in fighting that war for a quarter-century, the United States also created powers and political habits capable of weakening democracy from within.
