Beyond U.S. Guarantees: can Europe defend the Baltic without American ground forces?

Europe’s ability to defend the Baltic states without U.S. ground forces tests NATO’s credibility and European autonomy. We study this as an allocation-under-uncertainty problem and quantify how speed, defensive depth, and structure drive deterrence outcomes in the Baltic theatre. We develop a transparent, hazard-based, distributional model that links reinforcement timeliness and depth to the time-varying risk of breakthrough, and we simulate outcomes via Monte Carlo (100,000 runs per scenario). Calibration targets 7/14/21-day horizons, parameters cover baseline posture, arrival-time distributions, and depth/exposure multipliers. Results show that limited but timely European reinforcements can stabilize the front, whereas larger yet delayed forces often fail to avert defeat. Layered defences suppress risk and amplify the gains from prompt arrivals. Policies that thin arrival-time tails (readiness, rapid mobility, permissions, and prepositioned stocks) deliver outsized risk reductions relative to like-for-like increases in late mass. Credible deterrence, therefore, hinges more on speed and structure than on mass, supported by NATO – EU coordination. The approach is reproducible and source-calibrated, and stress-tests tail risks and depth to inform posture choices. Europe’s capacity to act fast, in depth, and coherently will ultimately determine Baltic defence credibility.