Europe has reached a strategic crossroads. The ongoing geopolitical turbulence, from renewed pressure on transatlantic alliances to open conflict at the continent’s eastern borders, has pushed defence spending back to the top of the policy agenda. Under the 2025 ReArm Europe Plan, European Union member states are expected to increase defence spending by up to 1.5% of GDP over the next five years. 

But Europe’s vulnerability runs deeper than defence. For decades, the continent has run its economies, its homes and its industries on energy it does not control. The price shocks that followed Russia’s invasion of Ukraine were a brutal reminder: When a hostile power controls your gas supply, it controls your options. Households faced spiralling energy bills, governments scrambled to find alternative suppliers and companies that couldn’t absorb the costs folded. The current wars and instability in the Middle East have brought a new wave of fossil fuel shortage that threaten Europe’s prosperity and ability to defend itself.

Traditionally, security spending and the green transition have been framed as competing priorities.Since budgets are finite, the argument goes, every euro spent on a heat pump is a euro not spent on a tank. This framing is simplistic and dangerous. By continuing to rely on imported fossil fuels, Europe is subsidising its adversaries. To secure its future, Europe must treat green innovation not as a secondary environmental goal, but as a primary requirement for energy sovereignty.

The vulnerability of the status quo

Energy resilience rests on the two pillars of sovereignty and physical security. Europe is weak on both. Nearly 60% of the EU’s energy needs are met by net imports and heavily skewed towards oil and natural gas. This is a structural constraint that shapes every foreign policy calculation, every winter heating bill and every industrial investment decision.

Since 2021, European consumers have experienced extreme energy price volatility in the wake of the Covid-19 pandemic. In 2022, when Russia invaded Ukraine, wholesale gas prices in Europe spiked to more than 10 times their pre-crisis levels. The supply disruptions exposed how little margin Europe had built into its energy system.

Renewable energy not only reduces dependency on imports, it also creates more resilient energy sources. Wind, solar, hydro and geothermal energy are locally produced and cannot be embargoed. Unlike centralised power plants or cross-border pipelines, dispersed installations are far harder to disable in a coordinated attack.

Nonetheless, renewables create their own dependencies, particularly in the supply chains for the infrastructure. For example, Europe is highly dependent on imports for its supplies of critical minerals and batteries. However, there is a difference between being constrained on the construction of new energy sources and having current energy supplies cut off. 

Green tech as a capability

The military sector is a microcosm of this broader vulnerability. Operating under a NATO-wide “single fuel policy,” the EU’s armed forces rely almost exclusively on liquid fuel imports to keep aircraft flying and convoys moving. If rearmament simply means consuming more of that same imported fuel at greater scale, it may only result in a larger military that is more exposed to supply disruptions.

Green tech within the military isn’t a fantasy. The Swedish Armed Forces have already tested JAS 39 Gripen fighter jets using plant-derived biofuel blends with no loss in operational capability. The Giga PtX consortium led by Germany’s Rheinmetall, with partners such as INERATEC, Greenlyte Carbon Technologies and Sunfire, is developing a decentralised network of synthetic fuel plants that would allow European forces to produce fuel locally and without relying on the public grid.

The point is that energy transition within the military sector should not be ignored, yet 82% of military-related emissions are missing from national greenhouse gas inventories. Since the Kyoto protocol, military emissions have been treated as a national security issue, which made sense in the 1990s but now mask inefficiencies that need fixing. You cannot build a more resilient energy system on a foundation of wilful opacity.

Once you move beyond the either-or framing, sustainability starts to look less like an environmental concession and more like a force multiplier by enhancing operational resilience. Decentralised renewable sources reduce dependence on vulnerable supply chains – keeping bases functioning when pipelines are cut, extending how far and how long forces can operate in the field.

Beyond the battlefield, defence investment has driven major civilian breakthroughs. The internet was born from work initiated by the United States Defence Department’s Advanced Research Projects Agency (DARPA). Military investment in synthetic fuels and high-capacity batteries today is likely to accelerate Europe’s broader energy transition, reducing household energy costs and industrial dependence on imports.

A strategic inflection point

Every new fossil fuel-dependent military asset built in the next five years is a new point of strategic vulnerability, a new revenue stream for energy exporters with interests opposed to Europe’s, and a new obstacle to the continent’s energy independence.

If Europe frames this challenge correctly, rearmament will mean more than boots on the ground or ships at sea. It’ll mean a fundamental restructuring of the energy system that underpins everything else – military readiness, industrial competitiveness, household security and the continent’s ability to act freely on the world stage without remaining structurally dependent on other countries.