Putin’s war in Ukraine has pushed EU member states to revamp collective energy and climate action.The Russian invasion of Ukraine is changing the European security order as we know it. This DIIS Report sets out to analyse how the rapid changes in European security impact two decisive and inseparable policy areas: climate and energy.The swiftness and determination with which the EU has acted has surpassed the expectations of most. To fulfil Europe’s energy and climate ambitions, the EU is implementing the REPowerEU action plan at a rapid pace. The EU has quickly negotiated wide-ranging sanctions and slashed its dependency on Russian coal, oil and increasingly also gas. Member states have significantly limited their energy consumption and found alternative energy suppliers, avoiding the immediate energy crisis many feared. Common European action to ensure stable and affordable energy supply has been unprecedented.