The first act of the 21st century: on Tuesday, September 11, 2001, the country that was considered the great world power, with no other power comparable to it, suffered a deadly attack on its own territory, in its most populous city and at the center of economic power. Televised worldwide and without the need for translation, the coalition of planes against the Twin Towers, the Pentagon, and Pennsylvania revealed a new global threat until then underestimated: jihadist terrorism.
In an interview with La Tercera, various analysts explain how the 2001 attacks changed the way we see terrorism, the long-term consequences they had on international politics, and, ultimately, how that fateful Tuesday defined the following 25 years.
One of the easiest things to verify is how security controls at airports have changed. Regarding this, an article from NPR recalls: “It’s hard to believe now, but before we could arrive at the airport just minutes before the flight. We passed through a simple metal detector with shoes and coat on, and practically anyone could go directly to the boarding gate without a boarding pass, not even showing an ID.”
At that time, airport security in the United States was the job of private companies, generally contracted by airlines, and there were not very high standards to follow: generally, the least possible was done. Jeff Price, who worked in security at Denver International Airport in 2001, explained to NPR: “Before 9/11, security was almost invisible and designed to be that way. It was something in the background, the idea was that it could not be noticed, and that it did not interfere with airport operations.”
In an interview with La Tercera, Joseph Schwieterman, a public transportation expert from DePaul University, details: “Nowadays it’s hard to believe how lax security was at some airports before September 11. A boarding pass wasn’t even necessary. X-ray equipment was used, but rarely did they stop you to check carry-on luggage.”
In that sense, the analyst adds that since then, it has become a common idea to arrive two hours before a flight due to security lines. In his opinion, this has added more people waiting inside terminals, making the airport experience more congested and stressful.
“As stressful as the security process has become, it has undoubtedly created a safer environment. The combination of more stressful security lines and fully packed planes has made flying seem less carefree and enjoyable than before September 11,” Schwieterman indicates.
Although during the 20th century there were several examples of terrorist attacks worldwide, the collisions against the Twin Towers defined the “terrorist threat,” at least in the 2000s. During the 90s, Western governments feared chemical and biological weapons much more, especially after the Aum Shinrikyo attack in the Tokyo Metro.
Regarding this, Katharine Petrich, a counterterrorism expert at the Middlebury Institute of International Studies at Monterey, tells La Tercera that even if terrorism existed before 2001, it was the 9/11 attacks that “brought the idea home”: “Before September 11, the main terrorist attack in the American experience was the Oklahoma City bombing in 1995. The fight against terrorism became the guiding axis of U.S. security operations abroad after September 11, replacing in many ways the existential threat of communism, which had dissipated after the end of the Cold War.”
In that sense, Petrich comments that one of the most interesting changes in the fight against terrorism had to do with monitoring its financing: “The greatest global impact of September 11 was, in fact, the restructuring of the international financial system, which developed and integrated many more regulations against money laundering and ‘know your customer’ to curb terrorism financing.”
Brian Nussbaum, a national security and cybersecurity professor at the University at Albany, tells La Tercera: “Terrorism went from being a relatively marginal public policy issue to a central one after 2001, and although it had been excessively ignored before September 11, it likely later acquired disproportionate prominence in policy making.”
In his opinion, some simple measures, such as reinforcing airplane cockpit doors and improving information sharing between agencies, made a lot of sense. “However, there were also excesses, both in spending on counterterrorism in lower-risk areas and in commitments made at the expense of civil liberties, human rights, and other foreign policy objectives,” the expert emphasizes.
Petrich and Nussbaum comment that even after years in which the “jihadist threat” was present and numerous Islamist attacks occurred worldwide, today, at least in the United States, terrorism does not come from the Middle East.
“In the case of the United States, what worries me most are small groups and lone actors motivated by far-right ideologies, white supremacy, or accelerationism. I am especially concerned about the apparent increase in youth radicalization around these issues, especially in the United States. Large and sophisticated jihadist groups, such as Al Qaeda and the Islamic State, still represent a threat in Africa, particularly in the Sahel, but their capacity and interest in carrying out a 9/11-style attack in the United States is very low in 2026,” Petrich says.
Nussbaum shares the diagnosis: “Jihadist terrorism remains a serious threat, but since September 11, terrorism perpetrated by white supremacists, antigovernment extremists, and other groups has been, overall, more lethal in the United States. Also, new forms of terrorism based on misogyny and motivations associated with ‘incels,’ as well as various conspiracy theories, have also become serious threats.”
Regarding this, Nussbaum points out that even though Islamist attacks have caused many deaths in recent years, a greater number of small attacks have been committed since 2001 by what the think tank New America defines as “far-right attackers.” And indeed, these latter “have ended up killing more people than the former.”
At the end of the 20th century, the United States was the great undisputed global power: unmatched economically or militarily, at that time the “ideological victory” of liberal democracy seemed total. Some of that began to collapse with the September 11 attacks, which concentrated subsequent U.S. efforts in the Middle East.
While the United States fought “endless wars” in Afghanistan and Iraq, China and Russia began to recover and more seriously threaten Taiwan and Crimea, respectively. Regarding this, international relations specialist at Carleton University, Aaron Ettinger, notes: “In 2001, the United States invaded and occupied Afghanistan, first to eliminate Al Qaeda and then to prevent that country from becoming a base of operations for terrorists. That second objective turned into a 20-year nation-building program, which ended in failure. After the U.S. withdrawal from Afghanistan in 2021, the Taliban returned to power.”
Regarding this, Ettinger recalls that the 2000s were considered by Time magazine as “the decade of hell,” both because of the wars that made the Middle East the great theater of world politics and because of the 2008 economic recession. “September 11, 2001, will remain a key date in U.S. history. For Americans, it marks the end of the post-Cold War period and the beginning of the ‘war on terror’ era. During the 1990s, there was considerable military intervention, economic pressure, and ideological influence by the United States worldwide, all aimed at consolidating liberal democratic capitalism. However, after 2001, the U.S. mindset shifted toward a grand strategy aimed at eliminating terrorism, especially that which had weapons of mass destruction,” the expert indicates.
“By 2008, the wars in Iraq and Afghanistan had become failed enterprises. Problems were worsened by the global economic crisis, which threatened the post-Cold War global financial order. By the 2010s, populist uprisings were observed worldwide against political and economic systems that seemed broken. Brexit and the rise of Trump are symptoms of that discontent,” Ettinger comments, seeing precisely a turning point in 2008, not only in the global economic crisis but also in the 2008 Beijing Olympics.
“I place the rise of China as a superpower at the opening ceremony of the 2008 Beijing Olympics, when it announced its power to the world. By the late 2010s, China already had enough strength to rival the United States in the Western Pacific, though not globally. Today, China tries to build a world order centered on itself, alongside the one the United States established after World War II. In 2026, multiple overlapping political orders coexist in the world,” Ettinger notes.
In the end, the expert comments, “the way the United States responded to 9/11 accelerated its own decline.”
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