Why the Afghan Army Collapsed Despite Years of Western Support
When the Defence Unravelled
The withdrawal of foreign support exposed an army built around dependence, while political isolation, failed resupply and Taliban bargaining turned military setbacks into a nationwide collapse.
On 15 August 2021, the Taliban entered Kabul as President Ashraf Ghani left Afghanistan. A government supported for almost two decades by the United States and its allies had disintegrated. Images of abandoned equipment and desperate evacuation made the outcome appear both sudden and inexplicable.
The collapse was rapid at the end, but its causes had accumulated over years. Afghan security forces depended on foreign military support, maintenance, logistics and political backing. Withdrawal weakened those foundations while the Taliban combined battlefield pressure with negotiations that encouraged isolated units to surrender.
The result was a chain reaction. Each lost district or provincial centre made neighbouring positions harder to supply and less confident of rescue. Forces that still possessed weapons could lose a credible reason to expect that fighting would change the outcome.
That is different from saying Afghans were unwilling to fight. Many had fought and died for years. The question is why their institutions ceased to sustain organised resistance when the external framework was removed.
What Exactly Collapsed?
The term “Afghan army” is often used to describe a much larger system. The Afghan National Defense and Security Forces included the army, police, air force and specialised units. Their roles, training, equipment and effectiveness differed considerably.
A police checkpoint in an isolated district did not possess the same capabilities as a commando formation. A pilot’s willingness to fly could not compensate for unavailable maintenance. A national manpower total could include people who were absent, unsuitable for front-line combat or employed in essential support duties.
These distinctions matter because public comparisons often treated the force as one enormous army confronting a smaller insurgency. The relevant military balance was more local and conditional. How many personnel were actually present? Did they have ammunition, food and functioning vehicles? Could they communicate with commanders and obtain reinforcement?
The final collapse involved more than lost battles. Chains of command weakened, local agreements multiplied, officials left, and the belief that a national defence would continue eroded. Political and military failure reinforced one another.
The Special Inspector General for Afghanistan Reconstruction, known as SIGAR, investigated both the security forces and the government. Its findings provide a major evidential foundation, although some conclusions were disputed by the US Department of Defense and the investigators faced limits on access. An official investigation is valuable evidence, not an excuse to ignore uncertainty.
The Biggest Reasons, Ranked
This ranking separates long-standing vulnerabilities from the decisions and events that accelerated the collapse in 2021. The order is an analytical judgement rather than a numerical allocation of blame. Several factors operated together, which is why no single explanation is sufficient.
1. Withdrawal Removed The Support On Which The Force Depended
SIGAR identified the decisions by the Trump and Biden administrations to withdraw US forces and contractors as a central trigger. The February 2020 US–Taliban agreement and the April 2021 announcement that withdrawal would proceed changed the expectations of Afghan officials, commanders and their opponents.
The effect was both material and political. Afghan forces had developed within a system that included foreign advisers, intelligence, air power, specialist maintenance and the assurance that a powerful ally remained directly invested in their survival.
Removing that framework did not leave an otherwise identical military with fewer foreign uniforms beside it. It changed what operations were feasible and what commanders believed would happen if they faced a major crisis.
For a local unit, the difference between promised future funding and accessible help could be decisive. Money allocated abroad cannot immediately evacuate casualties or reopen a blocked supply route. A commitment to continued assistance is not the same as a working support system at the point of need.
This ranks first as the principal accelerator of the final collapse. It does not mean maintaining the previous foreign presence forever would have produced a lasting settlement. It means the security system that existed in 2021 had not become independent enough to absorb the withdrawal on the terms and timetable adopted.
The critical distinction is between the argument for ending a war and the practical consequences of removing the support on which an allied force has been built.
2. The Army Had Been Built Around An Unsustainable Model
Withdrawal was the immediate shock; dependence was the underlying weakness that made the shock so destructive.
SIGAR found that the United States had trained and organised Afghan forces around methods requiring sophisticated support. The resulting force relied on systems that Afghanistan could not readily operate and sustain by itself. Its strongest elements, including the air force and special units, also needed outside assistance.
Building such a force can produce real short-term capability. Aircraft can move troops, evacuate wounded personnel and strike attackers. Specialised units can respond to emergencies that ordinary formations cannot manage. The problem arises when success is measured by what the combined system can do while its foreign components remain available.
A force may look progressively more capable without becoming progressively more independent. Those are different forms of improvement. If every gain requires maintenance, intelligence or financial administration supplied from outside, the appearance of maturity can conceal continuing dependence.
A more sustainable model would have required difficult choices about the size of the force, its missions, equipment and expectations. There is no guarantee that a simpler alternative would have defeated the Taliban. But the actual model demanded a level of support that was not going to continue indefinitely.
The lesson is broader than equipment selection. Training people to use a system is not the same as building the institutions needed to keep that system functioning under pressure.
3. Supply And Maintenance Failures Reached The Soldiers Who Had To Fight
An army’s resources matter only if they can be delivered to the units that need them. Afghanistan’s security forces struggled with the administration, movement and maintenance of those resources.
SIGAR’s investigation recorded serious problems in inventory visibility and distribution. Afghan officials described difficulties knowing what supplies were available and where they were located. Contractor dependence extended beyond fixing aircraft to the less visible work that allowed organisations to account for and allocate equipment.
The result was a gap between national holdings and local reality. A depot containing ammunition was not proof that a surrounded unit could obtain it. A serviceable aircraft elsewhere did not guarantee timely support for a checkpoint. Equipment awaiting maintenance could remain on the books while contributing little to the battle.
Such problems affect confidence as well as physical capability. Soldiers who repeatedly fail to receive supplies may reasonably question whether commanders can support the next operation. Each unanswered request can weaken the credibility of the next order to hold position.
It is important not to imply that every aircraft stopped flying or every unit ran out of ammunition on the same day. Capabilities declined unevenly. Some personnel continued operating under extraordinary strain.
That unevenness helped create the final pattern. Isolated formations became vulnerable while scarce effective forces were asked to cover an increasing number of emergencies. The military system lost the ability to make its remaining resources available where they could prevent the next defeat.
4. The Taliban Used Negotiation To Make Military Pressure Spread Faster
The Taliban’s victory was not simply a continuous series of frontal assaults. Its campaign also exploited local arrangements, intimidation and offers of surrender.
Such bargaining could be especially effective when a unit believed reinforcement was unlikely. The choice was no longer presented as victory or defeat in an abstract national struggle. It could become a question of whether to keep fighting in isolation, attempt escape or accept an agreement whose terms might appear preferable to being overrun.
These agreements should not be mistaken for universal enthusiasm for Taliban rule. Accommodation under threat can reflect fear, exhaustion or the judgement that the government cannot protect those who continue resisting. Nor should promises of safe passage be assumed to have been honoured consistently.
The mechanism was cumulative. A surrendered position freed Taliban fighters to concentrate elsewhere, transferred equipment and damaged the confidence of neighbouring defenders. The next negotiation took place in a more favourable setting for the insurgents.
The Taliban also understood the political value of demonstrating momentum. If officials and commanders believed the movement would ultimately win, they had incentives to make arrangements before their own bargaining position disappeared.
This is why the speed of the final collapse cannot be explained only by battlefield ratios. A force can expand its effective advantage by persuading parts of the opposing system to stop functioning before every position has been physically defeated.
5. Political Decisions Weakened Command When Coordination Was Most Needed
Afghanistan’s security institutions were not insulated from the government’s internal struggles. Appointments, personal loyalties and distrust affected the organisation expected to defend the state.
SIGAR criticised Ghani’s reliance on a narrow circle and the politicisation of the security forces. Research by Timor Sharan for the Afghanistan Analysts Network also examined how centralisation and political interference damaged military effectiveness in the Republic’s final period.
A central government needs authority over its armed forces. The problem is not civilian control itself. It is the replacement of reliable professional relationships with decisions that leave commanders uncertain of their position, disconnected from local realities or unable to act with confidence.
Leadership changes can be necessary during a crisis, but they also carry costs. A new commander needs to understand personnel, supplies and the local political environment. Repeated changes can interrupt planning precisely when the situation demands continuity.
Centralisation creates another danger if local problems must pass through an overloaded national decision-making process. Authority can appear strong at the top while responses become slow and confused below.
The effect was not identical in every province or formation. Some commanders performed effectively despite the institutional setting. But the government struggled to turn remaining military capability into a coherent national response, and that failure made local reverses harder to contain.
6. The Government Had No Credible, Implementable Plan For The New War
Once direct foreign support was being withdrawn, the Afghan government needed a military and political strategy that matched the resources it would actually retain.
SIGAR found that it failed to establish an effective national security plan for the changing circumstances. Its separate government assessment also concluded that leaders had not fully accepted that the United States would leave, leaving them insufficiently prepared for the consequences.
There were difficult choices available, none painless. Defending every district could disperse forces too widely. Concentrating on cities and major routes could abandon communities, undermine legitimacy and give the Taliban additional freedom. A negotiated settlement required compromise from parties that did not agree on the future political order.
The problem was therefore not that an obvious, cost-free solution went unused. It was that institutions were expected to hold a deteriorating position without a shared and feasible account of what they were trying to preserve or how they would do it.
A plan must do more than name important places. It needs forces that can reach them, supplies that can sustain them, commanders who understand the priorities and political authority willing to accept the sacrifices involved.
Without those conditions, requests to defend everywhere can become promises to defend nowhere reliably. Units receive obligations without the means to fulfil them, and local decisions replace national strategy.
7. Corruption And Weak Legitimacy Had Hollowed Out Resilience
Corruption did not suddenly appear in August 2021. It had long damaged the relationship between resources, institutions and public confidence.
Diversion of supplies, patronage and unreliable personnel reporting could make a force weaker than its official description suggested. The effects were practical: money that did not produce trained personnel, equipment that did not reach its intended destination and soldiers who could not trust that the system would meet their basic needs.
Legitimacy operated beyond the barracks. People’s willingness to provide information, accept government authority or risk cooperation depended partly on their experience of officials and security forces. A government can retain genuine supporters while losing enough trust to make its survival more difficult.
It would be wrong to treat corruption as an explanation for every Afghan decision, or to assume that foreign organisations were detached observers of the system they financed. Reconstruction incentives, short time horizons and pressure to demonstrate progress also shaped the institutions that emerged.
Nor did the Taliban offer a simple alternative of universally legitimate government. It used coercion and violence and faced opposition. The relevant question is why the Republic could not maintain a sufficiently dependable coalition of soldiers, officials and communities when the crisis intensified.
Corruption ranks below the immediate triggers because a corrupt system can persist for years with substantial external support. It became especially dangerous when that support weakened and the institution needed reserves of trust and competence it had failed to build.
8. A Cascade Of Falling Positions Destroyed Confidence In A National Defence
The final acceleration came from the interaction between military events and expectations. A lost position changed the situation elsewhere, even before the Taliban arrived there.
Neighbouring units could lose a supply route, a potential reinforcement source or confidence that their own commanders had a workable plan. Officials might leave. Families might urge soldiers to return. Local leaders might negotiate because other leaders had already done so.
This does not mean the collapse was imaginary or caused by social media alone. The underlying military pressure was real. Expectations amplified that pressure by changing behaviour across the system.
The distinction explains how forces with weapons and personnel still available could cease to constitute an effective army. Military power requires people to coordinate their actions on the assumption that other parts of the institution will perform their roles. When that assumption breaks, remaining resources may not combine into resistance.
Kabul’s fall was therefore both a culmination and a further shock. Ghani’s departure removed the political leadership at the moment when continuity was most urgently needed, but it did not create all the preceding provincial defeats.
The cascade ranks eighth because it describes the final mechanism through which earlier weaknesses became a national outcome. Treating it as a sudden, unexplained disappearance misses the conditions that made each local decision more consequential.
Why “They Would Not Fight” Is An Inadequate Explanation
Afghan personnel had fought for years and suffered heavy losses. Some units resisted fiercely during the final offensive. Others surrendered, dispersed or fled. A serious explanation has to account for that variation rather than assigning one national character trait to everyone.
Willingness to fight depends partly on what fighting can plausibly achieve. Soldiers may accept enormous risk when they believe a position can be held, casualties will be treated and other formations will support them. Their judgement can change when those expectations disappear.
That does not excuse every abandonment or erase cases of poor leadership. It places individual conduct within the system that made sustained defence possible or impossible.
The same distinction applies to equipment left behind. An abandoned vehicle can look like evidence of waste or cowardice in a photograph. Without knowing whether it had fuel, spare parts, an available crew or a viable escape route, the photograph cannot explain the decision that produced it.
Blaming the final soldier in the chain is often easier than examining the design of the chain. It is also less useful for understanding why an institution supported by so much money and training proved unable to survive the withdrawal of its external partners.
Did The Doha Agreement Hand Afghanistan To The Taliban?
The February 2020 agreement was a major turning point, but describing it as a complete transfer of power compresses a complicated process.
The Afghan government was not a party to the US–Taliban agreement. That exclusion weakened its position and elevated the Taliban’s standing as the organisation negotiating directly with the United States. The promised withdrawal also altered calculations about who would remain in Afghanistan after foreign forces departed.
The agreement was intended to lead towards further Afghan negotiations. It did not itself establish an agreed and functioning political settlement between the Republic and the Taliban. The absence of such a settlement mattered when the withdrawal timetable continued and military pressure intensified.
SIGAR’s government assessment criticised both the Republic’s negotiating approach and the Taliban’s unwillingness to compromise. The Taliban increasingly believed it could win militarily. A party expecting victory has less reason to accept limits it considers avoidable.
The agreement therefore contributed to the conditions of collapse without being the only cause. It acted on institutions already affected by dependence, internal division and years of war. The subsequent implementation of withdrawal and the choices made by Afghan leaders remained consequential.
Could Keeping A Small Foreign Force Have Prevented The Collapse?
Continued foreign support might have prevented or delayed the particular collapse that occurred in August 2021. That possibility should not be converted into certainty that a small, unchanged deployment could have maintained stability indefinitely at little cost.
The military conditions surrounding a decision to remain would have mattered. If the withdrawal agreement had broken down, attacks on foreign forces might have increased. Protecting bases, contractors and advisers could have required additional resources and a willingness to resume a larger combat role.
Keeping troops could also preserve the dependence that made withdrawal so difficult. Preventing collapse for another year is a meaningful achievement for people protected during that year, but it is different from establishing a self-sustaining political and security order.
Conversely, recognising those costs does not prove that the actual withdrawal was planned or executed as well as possible. Alternatives could include a different timetable, clearer contingency preparations or a more realistic earlier approach to force development. Each would need assessment against the conditions at the time.
The useful counterfactual asks what specific capabilities would remain, who would sustain them, what the Taliban would do and how long the arrangement could endure. Simply adding “a few troops” to the story leaves the most important questions unanswered.
What The Official Investigations Can And Cannot Establish
SIGAR’s reports are unusually valuable because they examine both the immediate collapse and the long history of building Afghan institutions. They also distinguish the security forces’ failure from the wider failure of government.
However, retrospective testimony has limits. Former officials may remember events selectively, disagree about responsibility or seek to defend their own decisions. The investigators encountered disputes over access and conclusions. These qualifications should accompany the evidence rather than be used to dismiss it entirely.
The reports are strongest when several forms of evidence converge: known dependence, documented decisions, institutional weaknesses and the sequence of events. They are less suitable for claiming that one personality or one conversation alone determined the outcome.
A ranking is therefore a way of organising the explanation, not a replacement for the complexity. Withdrawal, military design, Taliban action and Afghan political choices interacted. Changing one could have changed the timing or form of collapse without necessarily resolving the others.
The Difference Between Building A Force And Building Independence
Afghanistan’s collapse exposed a weakness in how military assistance can be judged. Equipment delivered, personnel trained and units established are visible achievements. The ability to continue operating when the donor leaves is harder to demonstrate and easier to postpone.
A sustainable force needs its own dependable methods for recruitment, leadership, supply, maintenance and political accountability. Those institutions may be less impressive in a presentation than aircraft or elite units, but they determine whether the visible capabilities remain usable.
In 2021, the withdrawal did more than reduce available support. It revealed how much of Afghanistan’s apparent military strength belonged to a combined international system rather than to institutions that could function alone.
The question for future assistance programmes is consequently very specific: if external personnel, money or political guarantees change, which capabilities still work the next morning, the next month and the next year? Afghanistan’s final collapse was the moment when too many of those answers became clear at once.
Sources
SIGAR — Why the Afghan Security Forces Collapsed, February 2023 — Military dependence, withdrawal, leadership, logistics, Taliban action and the investigation’s limitations.
SIGAR — Why the Afghan Government Collapsed, November 2022 — Political decision-making, negotiations and the Republic’s failure to prepare for withdrawal.
Afghanistan Analysts Network — What Went Wrong: The 2021 Collapse of Afghan National Security Forces — Timor Sharan’s analysis of political interference and the security institutions’ deterioration.
Next Reads
What If Afghanistan Was Never Invaded? — Consider the alternative choices confronting the United States after September 2001.
Why America Lost the Vietnam War: The 10 Biggest Reasons, Ranked — Compare military assistance with the harder task of sustaining an allied state.
The History Of Al-Qaeda: Afghanistan, 9/11 And Beyond — Understand the movement central to the original intervention and its wider history.
