Twenty-five years ago, on September 11, 2001, the world watched in horror as four commercial aircraft were turned into weapons of mass murder.

Two planes crashed into the World Trade Centre in New York. Another slammed into the Pentagon. Passengers aboard the fourth fought back against the hijackers before the aircraft crashed in Pennsylvania. Nearly 3,000 people were murdered that morning.

But 9/11 was not merely an attack on the United States. It attacked the post-Cold War assumption that globalisation, prosperity, and technological advancement had made large-scale ideological violence a relic of the past.

The men who hijacked those aircraft demonstrated something far more frightening: a determined extremist organisation could exploit the openness of modern societies to wage war against them.

Twenty-five years later, that lesson remains painfully relevant.

The banners have changed. The organisations have mutated. The geography has shifted. The methods have evolved. But the ideology that inspired 9/11 has not disappeared.

If anything, the post-9/11 history of terrorism demonstrates that Islamist terrorism has proved extraordinarily resilient.

That statement needs an important qualification. Islam and Muslims are not synonymous with Islamist terrorism. Hundreds of millions of Muslims across the world reject terrorism and have themselves been among its victims. Islamist terrorism is an extremist political ideology that invokes an absolutist interpretation of Islam to justify violence. Conflating an ideology with an entire religious community does nothing to defeat that ideology.

But refusing to name the ideology does not defeat it either.

And that is perhaps one of the great failures of the last 25 years.

The death of Al-Qaeda was repeatedly predicted. It never happened.

Osama bin Laden is dead. His organisation was hunted across continents. Its leadership was degraded. Afghanistan was invaded. Airport security was revolutionised. Intelligence agencies were transformed. Counter-terrorism cooperation became a permanent feature of international diplomacy.

Yet Al-Qaeda survived.

The Islamic State subsequently emerged from the wreckage of Iraq and Syria, captured enormous territories, proclaimed a so-called caliphate and attracted recruits from countries thousands of kilometres away.

When its territorial caliphate was dismantled, the problem did not disappear.

The organisation simply reverted to what terrorist networks have historically done when they lose territory: decentralise, adapt and metastasise.

Twenty-five years after 9/11, Al-Qaeda remains a significant, though diminished, force within global jihadism, while its affiliates continue to operate across Africa, the Middle East and South Asia. The ideology has survived the death of its most famous leader and the destruction of its most visible strongholds.

From skyscrapers to smartphones

Perhaps the most significant transformation has been technological.

The 9/11 terrorists required months of planning, international travel, flight training and a sophisticated logistical operation.

Today’s extremist does not necessarily require a terrorist training camp.

He can be radicalised online.

He can consume propaganda from a bedroom. He can communicate through encrypted platforms. He can be encouraged to conduct an attack without ever meeting a senior terrorist commander.

This is the terrifying evolution of the post-9/11 threat.

The terrorist organisation no longer necessarily needs to send the terrorist.

It can inspire him.

Islamic State has demonstrated precisely this ability to operate as an ideological franchise. Its territorial ambitions may have been crushed, but its affiliates continue to exploit instability, weak governance and social fractures across multiple theatres.

The battlefield has changed.

The war has not ended.

India has lived with the threat for decades

For India, the story of Islamist terrorism did not begin on September 11, 2001, and it certainly did not end with the death of Osama bin Laden. The country has endured repeated terrorist attacks, bomb blasts, targeted killings and cross-border jihadist violence for decades.

The Parliament attack, the Mumbai attacks and numerous bomb blasts across Indian cities demonstrated that India was already confronting the same broader phenomenon that the rest of the world would come to know with even greater urgency after 9/11.

The 2025 Red Fort blast was another chilling reminder that the threat is not merely historical. The investigation into the November 10 explosion near Delhi’s Red Fort uncovered what authorities described as a sophisticated terror module involving medical professionals, explosives, financial transfers and alleged links to Jaish-e-Mohammed. Investigators traced a substantial financial trail, recovered large quantities of explosive material and uncovered evidence suggesting that members of the network had been receiving bomb-making material and instructions from handlers abroad. The investigation also revealed an attempt to recruit a suicide bomber and a wider network spread across multiple locations.

What makes the case particularly disturbing is the apparent transformation of educated professionals into participants in a terrorist conspiracy. According to the investigation material, the network included doctors allegedly connected to Jaish-e-Mohammed and an extremist ecosystem involving encrypted communication, ideological indoctrination, financial inducements and bomb-making expertise. Investigators also recovered evidence relating to what was described as “Operation Hamdard”, reportedly involving the recruitment and training of young women for terrorist activity.

India’s experience also fits into a much larger global pattern.

In January 2015, Islamist terrorists stormed the Paris offices of the French satirical newspaper Charlie Hebdo, killing journalists, cartoonists and others in an attack carried out in the name of avenging what the perpetrators described as an insult to the Prophet Muhammad.

The attack became one of the defining terrorist atrocities in Europe after 9/11 because it demonstrated how extremists could interpret criticism, satire or perceived blasphemy as a justification for murdering civilians.

A decade later, the pattern remained tragically familiar.

On April 22, 2025, terrorists attacked tourists at Pahalgam in Jammu and Kashmir, killing 26 people. The attack by Pakistan-based terrorists was horrifying because the victims were reportedly asked their religion before being shot. The terrorists checked victims for circumcision, turning religious identity into a potential death sentence. India subsequently launched Operation Sindoor against terrorist infrastructure in Pakistan and Pakistan-occupied Jammu and Kashmir.

The message was unmistakable: Islamist terrorism remains capable of targeting civilians not merely because they are in the wrong place, but because of who they are.

Terrorism survives when states provide sanctuary

There is another dimension of the post-9/11 story that cannot be ignored: terrorists do not always operate in a vacuum.

They require financing, training, weapons, communications infrastructure, safe houses and, most importantly, sanctuary.

And sometimes that sanctuary comes from states.

Pakistan’s relationship with jihadist organisations is perhaps the most consequential example.

It is worth remembering the extraordinary circumstances surrounding the death of Osama bin Laden. The architect of the 9/11 attacks was killed by US forces in 2011 in Abbottabad, Pakistan, where he had been living in a compound not far from the Pakistan Military Academy. The discovery of the world’s most wanted terrorist living for years in a major Pakistani military town raised obvious questions about how such a high-value fugitive could remain there undetected.

The episode remains one of the most powerful symbols of the problem of terrorist sanctuary.

The issue is not simply that Pakistan failed to find bin Laden.

It is that organisations such as Lashkar-e-Taiba and Jaish-e-Mohammed have for decades operated from Pakistani territory, with extensive evidence of their networks, fundraising structures and leadership infrastructure there. The Lashkar-e-Taiba, in particular, has historically been nurtured and used by Pakistan’s intelligence establishment as a proxy against India.

The problem became impossible to ignore after Operation Sindoor.

Following the Pahalgam massacre, India launched strikes on May 7, 2025, against nine terrorist infrastructure sites in Pakistan and Pakistan-occupied Jammu and Kashmir. India’s Ministry of Defence said the targets were terrorist infrastructure from which attacks against India had been planned and directed. Later, the government said more than 100 terrorists, trainers, handlers and associates were killed in the strikes.

The significance of Operation Sindoor went beyond the destruction of terrorist camps.

Images and videos that emerged after the strikes showed Pakistani military personnel and senior officials attending the funerals of terrorists killed in the attacks. Pakistani Army officers and Punjab police officials among those were present at funerals linked to slain Lashkar-e-Taiba and Jaish-e-Mohammed figures. In one case, a funeral for a senior Lashkar figure was conducted with military honours, with wreaths laid on behalf of the Army Chief and Punjab’s Chief Minister.

Later, a Jaish-e-Mohammed commander claimed that Pakistan Army leadership had instructed officers to attend the funerals, revealing a deep nexus between terrorism and the state’s armed forces.

The imagery was extraordinary.

India had just struck the infrastructure of terrorist organisations responsible for years of bloodshed, and the men who had been killed were subsequently accorded a degree of recognition involving serving Pakistani military personnel.

Such scenes reinforce a conclusion that India has reached repeatedly over decades: cross-border terrorism cannot be understood solely as the work of non-state actors when those actors have operated from territory where state institutions possess considerable reach and authority.

This is the fundamental challenge posed by state-sponsored terrorism.

A terrorist organisation can be defeated militarily. But if another state provides it sanctuary, training, financing, diplomatic protection or strategic utility, the organisation can regenerate.

You can kill the terrorist.

You cannot permanently eliminate the threat while the ecosystem that produces him remains intact.

The uncomfortable truth about ideology

The world became very good at identifying terrorists.

It became less comfortable discussing the ideology that motivates them.

There is nothing courageous about pretending that ideology does not matter.

Terrorism does not emerge from nowhere. Organisations recruit. Propagandists indoctrinate. Political grievances are weaponised. Young people are persuaded that murder can become an act of Islamic piety.

Defeating terrorism therefore requires more than killing terrorists.

It requires defeating the intellectual and ideological infrastructure, i.e Islamism, that produces them.

That means confronting Islamist extremist propaganda. It means dismantling terrorist financing networks. It means preventing radicalisation in prisons, online communities and vulnerable populations. It means holding states driven by Islamic doctrine accountable when they provide sanctuary, infrastructure or diplomatic cover to terrorist organisations.

And it means refusing to sanitise Islamic terrorism through euphemisms.

A terrorist who murders civilians does not become less of a terrorist because his political objective is inconvenient to acknowledge.

The same standard must apply everywhere.

The West learned the wrong lesson from victory

There is another danger in the 25th anniversary of 9/11: complacency.

Counter-terrorism works.

Intelligence cooperation works. Financial sanctions work. Military pressure works. Border controls work. International cooperation works.

But success against terrorism is not the same thing as victory over terrorism.

The destruction of the Islamic State’s territorial caliphate was a major achievement. The killing of bin Laden was a major achievement. The dismantling of terrorist cells and disruption of financing networks have saved countless lives.

But terrorist movements are patient, especially the Islamic terror networks, who routinely invoke Islam and religious scriptures to derive validity and support among the gullible population willing to be radicalised for carrying out ‘Jihad against infidels’.

They wait for wars, political instability, weak governments, porous borders and social fractures.

They exploit chaos.

And when governments become complacent, they return.

Twenty-five years later, the question remains.

The defining lesson of 9/11 is not simply that terrorists can destroy buildings. It is that extremist ideology can turn ordinary human beings into instruments of mass murder.

It is also that terrorism becomes dramatically more difficult to defeat when terrorist organisations receive sanctuary from states.

Twenty-five years after 9/11, the world is no longer fighting the same enemy in the same places with the same weapons.

Al-Qaeda survives. Islamic State survives. Their affiliates survive. New generations are being exposed to extremist propaganda. Terrorist groups are exploiting failed states, civil wars, social media and emerging technologies.

And state support or sanctuary continues to complicate the fight.

India’s experience makes the warning even sharper. From repeated bomb blasts over the past quarter-century to attacks targeting civilians, security forces and tourists, India has had little opportunity to indulge in the illusion that Islamist terrorism belongs to a bygone era.

The Red Fort investigation is a particularly stark reminder that the contemporary terrorist threat can involve educated professionals, sophisticated financing, foreign handlers, encrypted communication and readily available materials being repurposed for mass-casualty attacks.

Pahalgam demonstrated that terrorists can still select victims according to religious identity. Charlie Hebdo demonstrated that Islamic terrorists can turn an alleged insult into a justification for murder. Abbottabad demonstrated the extraordinary challenge posed by terrorist sanctuary. And Operation Sindoor demonstrated that destroying terrorist infrastructure may require striking beyond the immediate battlefield when terrorist organisations are operating from across an international border.

Twenty-five years after 9/11, therefore, the central question is not whether Islamic terrorism has been defeated.

It plainly has not.

The question is whether the world is prepared to sustain the political, intelligence, military and ideological effort required to defeat it.

Because terrorist organisations can lose territory and regain influence, they can lose leaders and recruit replacements. They can lose training camps and move online. They can lose one generation of terrorists and radicalise another.

And when they have the protection, tolerance or strategic patronage of states, their ability to survive becomes even greater.

The battlefield may change.

The propaganda may change.

The methods may change.

But the ideology remains.

Twenty-five years after 9/11, the world therefore needs more than remembrance. It needs clarity.

The nearly 3,000 people murdered on September 11 deserve to be remembered. So do the victims of Mumbai, Paris, Pahalgam and countless other terrorist attacks whose names never became global headlines.

But remembering them also means remembering what killed them.

It means recognising Islamist terrorism as an enduring transnational threat, confronting the ideology that legitimises it, dismantling the organisations that operationalise it and holding accountable the states that provide terrorists with sanctuary or support.

Because the war against Islamic terrorism was never won simply by killing Osama bin Laden.

His death was a victory.

It was not the end of the war.

And twenty-five years after the planes struck New York and Washington, that war remains unfinished.