International Sovereignty Index (ISI) — EU-27 Country Brief Series (2024), Paper 4 (v1.0)

This report presents the EU-27 country brief series of the International Sovereignty Index (ISI) based on vintage-2024 data under methodology v1.0. The International Sovereignty Index (ISI) is a six-axis composite indicator measuring the concentration of external supplier relationships across strategically relevant domains: finance, energy, technology, defence, critical inputs, and logistics. Each axis is constructed using Herfindahl–Hirschman–type concentration metrics normalised to the unit interval and aggregated into the ISI composite score. The present record contains 27 individual country briefs and a consolidated EU-27 country brief report. Each brief summarises the structural supplier-concentration profile of a single EU member state, reporting: the ISI composite score axis-level concentration values EU-27 rankings a concise analytical interpretation of the country’s external dependency structure Core ISI Publications The country brief series complements the core publications of the International Sovereignty Index (ISI) Paper Series: ISI Paper 1 — Technical Specification (v1.0) DOI: https://doi.org/10.5281/zenodo.18764227 ISI Paper 2 — EU-27 Empirical Results (2024, v1.0) DOI: https://doi.org/10.5281/zenodo.18764170 ISI Paper 3 — External Supplier Concentration in the EU-27: Empirical Findings (2024, v1.0) DOI: https://doi.org/10.5281/zenodo.18818748 Together, these documents establish the methodological framework, empirical dataset, and interpretive analysis underlying the index. Project Objective The International Sovereignty Index (ISI) aims to provide a transparent and reproducible measurement framework for analysing structural external dependencies of sovereign economies, enabling comparative analysis of supplier concentration across countries and strategic domains. All methodology, data architecture, and computational procedures are publicly documented and reproducible.