The potential costs of defending Europe without a US security guarantee are coming into focus as European allies consider a future with reduced or no US involvement. A report by think tanks Bruegel and the Kiel Institute for the World Economy warns that Russia’s military has become significantly larger, more experienced, and better equipped since its invasion of Ukraine three years ago.
The report estimates that Europe would need to boost end strength by 300,000 troops to match the combat power of 100,000 US troops already stationed in Europe. However, this would require a significant increase in defense spending, estimated at €250 billion annually, equivalent to 3.5% of GDP.
European governments face challenges in funding such an effort, with Germany’s “debt-brake” rule and France’s high debt-to-GDP ratio posing obstacles. Some propose collective borrowing for one-off investments or borrowing from the European Investment Bank to finance defense projects. A former economic adviser suggests that upping defense spending is less costly than fighting an all-out war.
The prospect of a US withdrawal has prompted Denmark to boost its defense spending by 70%. Intelligence services warn that Russia could launch a local war within six months, a regional war in the Baltics within two years, and a large-scale attack on Europe within five years. Without significant investment in military capabilities, European militaries would be at risk of being overwhelmed.
Source: https://fortune.com/2025/02/23/american-troops-european-armies-nato-russia-war-us-security-cost