9/11

The Long Shadow of 9/11 for Europe’s Defence

When four hijacked airliners struck the World Trade Center and the Pentagon, and a fourth crashed into a field in Pennsylvania, the attacks caused a seismic shock across the Western world. The brutal attacks on the United States twenty-five years ago marked a watershed moment in international security. Many of the consequences became visible in the years that followed, including the securitisation of everyday life, a decade of Western presence in Afghanistan and the start of a wider fight against jihadist terrorism at home and abroad.

Less visible was another development whose consequences Europe is still dealing with today. The wars that followed 9/11 accelerated a fundamental transformation of European armed forces. Territorial defence, mass land armies and large mobilisation structures were replaced by rapidly deployable, professional forces able to operate thousands of kilometres from home.

This transition came at a price. When Russia annexed Crimea in 2014 and launched a full-scale invasion of Ukraine in 2022, European countries quickly learned that they were ill-prepared for the most important security challenges of our time.

NATO in Afghanistan

Following 9/11, the United States became the first, and so far only, NATO member to invoke NATO’s mutual defence clause, Article 5 of the North Atlantic Treaty. European allies joined the US-led intervention in Afghanistan, and NATO subsequently took command of the International Security Assistance Force, or ISAF.

Afghanistan became NATO's most ambitious military operation beyond the Alliance's traditional area. At its height, tens of thousands of European soldiers served as part of the ISAF mission. Many European countries paid a high price in doing so, as a third of the coalition’s casualties were European.

It also meant that the European NATO members had to rapidly redesign their capabilities to sustain a large-scale foreign deployment. This was done by investing in specific capabilities such as strategic airlift, out-of-area intelligence gathering, special forces, and protected patrol vehicles. However, it also came at the expense of conventional capabilities that served NATO’s previous focus on land war in Europe.  

From territorial defence to expeditionary force

The shift from territorial defence to expeditionary forces took place as part of a longer trajectory of transition. After the end of the Cold War, European governments were keen to downsize their armies and cash in on the “peace dividend”. Defence budgets fell, armies shrank, and the possibility of a conventional war on the European continent became increasingly unlikely.

The military interventions in the Balkans in the early 1990s gave a first push towards the professionalisation and deployability of Europe’s armed forces. European governments started to adapt to the needs of crisis response and peacekeeping operations. In the NATO context, a consensus emerged in the mid-1990s that the alliance should “go out of area or out of business.”

Acceleration after 9/11

The international response to the 9/11 attacks rapidly accelerated this doctrinal development. Force models that were previously aimed at mass and endurance were successfully transformed into rapidly deployable, flexible forces with the aim of deploying relatively small contingents abroad.

In Germany this process culminated in the 2011 reform of the Bundeswehr. Led by then-Defence Ministers Karl-Theodor zu Guttenberg (CSU) and Thomas de Maizière (CDU), the initiative abolished conscription, cut the number of troops from 250.000 to 185.000, and made foreign missions the Bundeswehr's main priority.

Germany was not alone in this, as the UK aggressively cut its conventional capabilities in the 2010 & 2015 Strategic Defence and Security Reviews and France fully adapted its army for rapid interventions in the "arc of crisis" running from the Atlantic to the Indian Ocean. The Netherlands even went as far as selling its remaining Leopard 2 tanks in 2011, effectively giving up an independent tank capability. Expeditionary force became the benchmark of modern military, while territorial defence was seen as increasingly irrelevant to serve national security interests.

Much of today’s criticism on the state of Europe’s armed forces is aimed at the defence budget cuts in the 1990s and 2000s. Although justified, this is only part of the story, as the impact was exacerbated by replacing territorial defence capabilities with capabilities for missions abroad. European forces not only decreased in size, but they were also redesigned for a different type of warfare.

U-turn after Russia’s invasion of Ukraine

Russia’s annexation of Crimea in 2014 reversed the trend and marked the beginning of a new focus on territorial defence in Europe. Eight years later, Russia’s full-scale invasion of Ukraine led to a full U-turn. Capabilities such as heavy armour, artillery, ammunition stocks and air defence were suddenly in high demand and short in supply. This has led European countries to boost defence spending to record levels and re-equip for the type of war that is being fought in Ukraine.

In the process, however, much of the structure and expertise needed to deal with a large-scale conflict on the European continent was lost. Rebuilding these capabilities now requires significant additional investment that might not have been necessary without the post-9/11 transformation of European armed forces. In a paper published earlier this year, King’s College London researcher Bence Nemeth argues that Europe’s shortfall in heavy combat power is primarily the result of deliberate doctrinal choices. His analysis shows that Canada, Germany and the United Kingdom would have been considerably better prepared to defend NATO’s Eastern Flank in 2022 had they not changed course, regardless of the reductions in defence spending. The case demonstrates that adapting armed forces to the demands of a specific conflict can create significant vulnerabilities in the future.

Lessons for the future

With Europe paying a premium for the U-turn in its military transformation, it is important to look at the lessons for the future. Although it is difficult what the next major conflict will look like, even more so with the war in Ukraine still ongoing, there are several

• Maintain openness to the future: Avoid designing entire armed forces around the conflict of the moment. Europe will likely need expeditionary forces in the future and it is important that the armed forces maintain and invest in these capabilities in the future.
• Stay flexible: create capacity to rapidly adapt to changes within a conflict. Over the course of the war in Ukraine, the focus has shifted from tanks and artillery towards drones, air defence, electronic warfare and increasingly ballistic missiles. It is unpredictable how conflict develops and European countries should therefore focus on building up industrial capacity, streamlined procurement processes and rapid innovation loops.
• Develop strategic depth: Europe should strengthen the European pillar in NATO through sustained, long-term investment in defence rather than responding to crises with temporary spending increases. This also requires developing a stronger strategic culture in which defence, preparedness and military power are treated as permanent elements of European security policy.

The legacy of 9/11 goes far beyond the horrific scenes of the day itself and their immediate effects. Europe is still coming to grips with the security implications, as it is trying to build up the defence structures it lost over the past decades. In doing so, Europe should not repeat the mistakes from the past. The most important takeaway is therefore that Europe should prepare for both the known and the unknown.