How America’s Response to 9/11 Led Straight Back to the Taliban in Afghanistan

How America’s Response to 9/11 Led Straight Back to the Taliban in Afghanistan

Twenty-five years after the September 11 attacks, one of the most striking legacies of America’s “War on Terror” remains Afghanistan: the United States invaded the country to remove the Taliban, fought its longest war there, and eventually withdrew as the Taliban returned to power.

The story is not a simple one of military defeat or political withdrawal. It is the result of two decades of changing objectives, an insurgency that survived after its initial defeat, weaknesses within the US-backed Afghan state, and a peace process that ultimately gave the Taliban a path back to national power.

From 9/11 to the invasion of Afghanistan

The attacks of September 11, 2001, carried out by al-Qaeda, transformed US foreign policy almost overnight.

At the time, al-Qaeda leader Osama bin Laden and his organisation were based in Afghanistan under Taliban rule. After the Taliban refused US demands concerning al-Qaeda and bin Laden, the United States and its allies launched military operations in October 2001.

With support from Afghan anti-Taliban forces, the US-led campaign rapidly removed the Taliban from control of major cities and Kabul. What initially appeared to be a swift military victory, however, soon developed into a much longer conflict.

The Taliban were removed, but not eliminated

The Taliban government collapsed in late 2001, but its movement did not disappear.

Many Taliban leaders and fighters regrouped in Afghanistan and across the border in Pakistan. From there, the organisation gradually rebuilt its networks and launched an insurgency against the new Afghan government, Afghan security forces and the international coalition.

This became one of the central problems of the war: the United States had succeeded in overthrowing the Taliban government, but it had not destroyed the Taliban as a fighting force or political movement.

America's mission kept expanding

The original US objective was closely tied to counterterrorism and the destruction of al-Qaeda's sanctuary.

Over time, however, the mission expanded. The United States and its allies became deeply involved in building a new Afghan state, training security forces, supporting elections and attempting to create institutions capable of surviving without foreign military backing.

That transformation created a much more complicated war.

Instead of simply pursuing terrorist groups, Washington was now trying to support a government in Kabul while fighting a persistent insurgency across large parts of the country.

The result was America's longest war, lasting from 2001 until 2021.

Why the Taliban survived

The Taliban benefited from several factors during the two-decade conflict.

The group maintained an insurgent structure that could retreat, regroup and return after military setbacks. It also exploited dissatisfaction with corruption and weaknesses in parts of the Afghan government.

Meanwhile, the Afghan security forces depended heavily on foreign funding, intelligence, logistics and air support. As long as US and NATO forces remained deeply involved, the Kabul government was able to survive. But that dependence would become critical once Washington decided to leave.

Analysts have continued to debate which factor was most important: Taliban military strength, failures of Afghan governance, shortcomings in the US-led nation-building project, regional dynamics, or the eventual withdrawal of foreign support. The collapse was the product of several of these forces rather than one single event.

The Doha agreement changed the endgame

After years of fighting, the United States began negotiating directly with the Taliban.

In February 2020, the Trump administration signed the Doha agreement with the Taliban. The deal set out a framework for the withdrawal of US forces, subject to commitments involving counterterrorism and other conditions.

The agreement was a major turning point because it established that the United States was preparing to end its military involvement after nearly two decades of war. The Afghan government was not itself a signatory to the US-Taliban agreement, adding further complexity to the political process.

Biden completed the withdrawal

When President Joe Biden took office, his administration reviewed the situation and decided to proceed with the withdrawal of remaining US forces.

As foreign troops began leaving in 2021, the Taliban launched a rapid nationwide offensive. Afghan forces collapsed far more quickly than many observers had expected, with provincial capitals falling one after another.

On August 15, 2021, Taliban fighters entered Kabul as the Afghan government effectively collapsed. The United States completed its military withdrawal later that month, ending the 20-year war.

The extraordinary result was clear: the Taliban had been removed from power in 2001, only to return to Kabul in 2021 after the departure of US and NATO forces.

Did the US achieve its original goal?

The answer depends on which goal is being measured.

The US-led invasion successfully removed the Taliban government that had hosted al-Qaeda and disrupted al-Qaeda's operations in Afghanistan. The killing of Osama bin Laden in Pakistan in 2011 was another major milestone in America's counterterrorism campaign.

But the broader attempt to build a stable, internationally backed Afghan state capable of surviving without US military support ultimately failed.

The Taliban's return therefore became one of the defining paradoxes of the post-9/11 era: America entered Afghanistan because of the Taliban's relationship with al-Qaeda, spent two decades trying to prevent the Taliban from returning, and left with the Taliban once again governing the country.

Afghanistan under the Taliban today

Five years after returning to power, the Taliban remains in control of Afghanistan, though the country continues to face serious economic, humanitarian and human-rights challenges.

The Taliban government has imposed sweeping restrictions on women and girls, including severe limits on education and employment. International recognition of the Taliban-led government also remains limited, while Afghanistan continues to deal with poverty, unemployment and humanitarian pressures.

At the same time, the post-withdrawal security picture has proven more complicated than early predictions. Afghanistan has not simply returned to the exact situation that existed before 2001, but militant threats remain a major concern, particularly from Islamic State Khorasan Province, or ISKP.

The lasting lesson of the post-9/11 war

America's Afghanistan experience remains a defining lesson in the limits of military power.

The US military could remove the Taliban government quickly in 2001. What proved far harder was building a political order strong enough to survive after American troops left.

That is why the story of 9/11 and Afghanistan forms a complete, if deeply ironic, circle.

The attacks brought America to Afghanistan. The Taliban were overthrown. A 20-year war followed. And when the United States finally left, the Taliban returned.

For many historians, policymakers and veterans, that sequence remains one of the most important questions of the post-9/11 era: how did the world's most powerful military spend two decades fighting the Taliban, only to see them back in Kabul at the end of the war?

As the US marks 25 years since 9/11, the answer continues to shape debates about military intervention, nation-building and the consequences of wars whose objectives change long after the first shots are fired.