ABSTRACT The differing reactions between Western nations and the Global South to Russia’s invasion of Ukraine present a puzzle. Shouldn't post-colonial states be just as concerned about the principles of national sovereignty and non-intervention as Western countries? The idiosyncratic, ad hoc explanations on a country-by-country basis are insufficient to account for a much broader phenomenon. This article deconstructs the “sovereignty principle” as it is seen in the Global South and examines the standing of the so-called Rules-Based Order (RBO), allegedly under mortal threat by Russia’s action. It then argues that a far better explanation for the Global South’s reaction is the rise of Active Non-Alignment (ANA). The foreign policy doctrine of ANA arose in Latin America in 2019–2020 in response to US–China tensions, It then spread to the rest of the Global South in 2022–2024 because of the war in Ukraine, BRICS expansion, and the war in Gaza.