It was September 11, 2001, when 19 terrorists associated with al-Qaeda hijacked four civilian airliners — two struck the twin towers of New York City’s World Trade Center (WTC) and one the Pentagon, while the fourth aircraft crashed in Pennsylvania. The WTC was completely destroyed, and a total of 2,977 people were killed in the 9/11 attacks. The dastardly act demonstrated a new face of the asymmetric warfare, wherein “non-state actors” (NSAs) operating from the distant sanctuaries could inflict strategic shock on a global superpower.The US responded swiftly by launching “Operation Enduring Freedom” a month later, on October 7. The aim was to dismantle al-Qaeda, remove the Taliban regime that had provided haven to the terrorists’ outfit, and capture or kill top leadership and high value targets — including al-Qaeda chief Osama bin Laden — by employing overwhelming force. Local Afghan forces like the “Northern Alliance” formed part of the US-led international coalition. The Taliban regime was quickly overthrown and what followed was the strategic expansion of counter terrorism operations.The GWOT became the organising framework of US national security. It basically entailed creating unprecedented global intelligence networks, special forces (small teams central to counterterrorism), intelligence-led precision strikes by armed drones, and scrutiny of terrorist funding. While the initial objectives were quite specific, the mission gradually expanded to counter-insurgency, regime change, and eventually nation-building. This fundamentally changed the complexion of war to “Forever War’.The US forces enjoyed overwhelming tactical and technological superiority. The satellites, signal intelligence, cyber capabilities, and networked command systems compressed the “sensor to shooter” cycle, from days to hours or even minutes. The al-Qaeda core leadership was dismantled, and bin Laden was eliminated in 2011 in Abbottabad-Pakistan. Even when the extremist group Islamic State of Iraq and Syria (ISIS) established the “Caliphate” (a self-proclaimed Islamic state spanning parts of Iraq and Syria), it too was annihilated.Also read | 25 years on, America’s response to 9/11 is its biggest self-inflicted hurtTactical edge, however, could not compensate for strategic outreach. The adage “winning battles does not necessarily mean winning the war” stood vindicated.The Iraq invasion in 2003 opened another theatre, diverted resources, and created vulnerabilities which were subsequently exploited by the extremist outfits. Although major combat operations under “Operation Enduring Freedom” concluded on December 28, 2014, broader involvement of US-led coalition forces continued subsequently.After two decades, the US forces withdrew from Afghanistan, having incurred enormous expenditure and extensive human cost. The departure of Major General Christopher Donahue, Commander of the 82nd Airborne Division, along with the last of US forces personnel on a C-130 aircraft from Kabul on August 30, 2021, marked the literal end of US military presence in Afghanistan.Story continues below this ad A UH-60L Blackhawk helicopter being loaded into a C-17 Globemaster III in support of the Resolute Support mission in Afghanistan on June 16, 2021. Photo: Wikimedia CommonsThe most enduring lesson of the US’s Afghan experience and perhaps of GWOT was: external military power can destroy terrorist infrastructure but cannot substitute for legitimate politics, effective governance, and indigenous institutions. Military interventions can create strategic space and the environment for political process but cannot ensure political legitimacy.The principal error in the GWOT was not the use of force — which was inevitable to destroy the al-Qaeda network — but losing sight of specific aims and missions. Terrorism is a tool of political violence, so it is crucial to address the political and socio-economic issues in which the extremist narrative thrives.Terrorism transformedTwo decades ago, terrorist organisations were comparatively hierarchical, with recognisable leadership, known sanctuaries and training camps, financing networks, and centrally planned operations. Currently, the terrorists’ outfits are networked, decentralised, digitised, and individualised lone actors.Also read | From 9/11 to Zohran Mamdani: From the ashes, a new South Asian political compactOutfits like al-Qaeda and ISIS have not totally disappeared but dispersed into parts of Africa, West Asia, and South Asia. New havens are weak states and civil war-prone regions or ungoverned spaces. The training is being imparted on smartphones instead of camps. The recruitment and radicalisation are now through encrypted communications and social media, without physical contact or formal organisation. Lone wolves or small autonomous cells can undertake violent acts with minimal warning.Story continues below this adTechnology is playing a significant role in this transformed terrorism. Commercial drones are being employed for reconnaissance and delivery of explosives. Artificial intelligence is being effectively employed for propaganda as well as psychological and cyber warfare. Cryptocurrencies and dubious financial channels make tracking complicated. Terrorism is increasingly becoming faceless, anonymous, and high-tech. The distinction between domestic and foreign terrorism is also becoming blurred.The US may finally close the chapter on 9/11, which began 25 years earlier. During the “war on terror”, while the US forces decimated al-Qaeda leadership and severely degraded the core, it did not end terrorism. Jihadist ideology, affiliates, and radicalised elements survived. But it changed the very nature of warfare and transformed terrorism. As things turned out, when the American forces pulled out, the Taliban were back in Kabul. Iraq proved that regime change is easier than building a stable political order. Tactical dominance did not translate into strategic outcomes — a paradox which shuns a simplistic analogy.NewsletterFollow our daily newsletter so you never miss anything important. On Wednesday, we answer readers' questions.SubscribeThe US paid a heavy price for being involved in West Asia and Afghanistan. While it was embroiled in GWOT, China rose rapidly and Russia reasserted itself, with great power competition returning to the centre stage. Ironically, the US is once again stuck in West Asia. History vindicates that ignoring past lessons turn out to be future blind spots.With technology as the new battlespace, inexpensive autonomous systems lend NSAs and proxy outfits significant capability to undertake operations that can generate strategic effect. Today, there is considerable overlap between conventional war and terrorism, leading to hybrid warfare. Only prevention and pre-emptive measures can eliminate the perpetual “never ending wars”. For this, coordinated real time intelligence, border management, financial disruption, and precise counterterrorism actions are key. So are good governance, counter radicalisation, and addressing conditions that extremist organisations tend to exploit.Story continues below this adAll said, 9/11 changed the very face of terrorism. The wars that followed exposed the limits of military power.The author is a war veteran and served as defence attache in China, North Korea, and Mongolia. He is currently professor of international relations, management at Lal Bahadur Shastri Institute of Management.