Europe’s defense spending is undergoing a historic shift. With NATO members expected to reach 2% of GDP and discussions underway to increase targets to 5% by 2035, this paper examines the possible macroeconomic consequences of such rearmament using two complementary approaches. First, using an annual panel dataset covering 27 EU countries over the period 1989–2023, we show that past national defense spending has stimulated economic activity in the short term, and entailed sizable cross-border spillovers. Importantly, we find that spending multipliers varied considerably across countries and over time: they tended to be larger when import intensity is low, fiscal space (captured by sovereign yields spread) is ample, and public investment efficiency is high. Second, a novel high-frequency dataset of monthly defense procurement contracts from Opentender, covering EU-27 countries from 2009 to 2023, allows for improved causal identification using fiscal news and instrumental variables based on European aggregate defense procurement and each country’s geographic proximity to major adversaries. The estimates corroborate the positive effects of defense spending on output and show that equipment procurement has the strongest relative impact. Given the larger and more synchronized nature of the current European defense buildup relative to past national episodes in our sample, multipliers might fall below historical estimates, especially if monetary policy is not accommodative.