This report examines twelve key Western nations, covering security and defence policy, military expenditures, armed forces structure, current operational military capability, and the development of military capability up to 2030. It encompasses how Russia's full-scale invasion of Ukraine catalysed various ongoing national deterrence and defence efforts, prompting new initiatives, including military assistance to Ukraine and its potential effects on national capability. The selection of the twelve countries-Denmark, Norway, Sweden, Finland, Estonia, Latvia, Lithuania, Poland, Germany, France, United Kingdom, and the United States-is based on their importance to the collective defence of Northern Europe. This report is part of the broader study, Western Military Capability in Northern Europe 2023, contributing to the aim of delivering a comprehensive analysis of the military strategic situation in Northern Europe. This multi-part study unfolds in two phases. The first phase establishes an empirical and analytical foundation. In the second phase, the results and insights will be amalgamated and leveraged, culminating in a so-called net assessment of Western military capability in Northern Europe.