This open access book provides an in-depth exploration of how presidents, prime ministers, and their cabinets manage relationships and make decisions in times of international crises. The authors focus particularly on war and its effect on executive dualism and presidential activism. This systematic analysis concentrates on four Central European countries - Poland, Czechia, Hungary, and Slovakia - and examines the ongoing Russian-Ukrainian war, as well as earlier conflicts: the Kosovo crisis (1999), the Iraq War (2003), the Russo-Georgian War (2008), and Russia's annexation of Crimea and the emergence of separatist "republics" in eastern Ukraine (2014). All these conflicts had a major political impact on the political landscape of Central Europe, often empowering presidents, who represent the state externally and influence foreign and security policies.