The instrumentalization of migration flows as state-sponsored pressure on the Belarus–Poland border: a model of coercion below the threshold of armed conflict

In 2021 the Belarusian state organised the movement of thousands of third-country nationals to its border with Poland, Lithuania, and Latvia, channelling them toward the European Union as a deliberate instrument of pressure. The episode crystallised a mode of coercion that uses people rather than weapons and that operates carefully below the threshold of armed conflict, yet existing scholarship has explained it mainly descriptively, through the lens of securitisation or of the law, without a model that specifies how the leverage is actually generated. This article develops that model. Its original contribution is the Sub-Threshold Coercion (STC) model of weaponised migration, built around a novel concept, the target's normative-entrapment dilemma, and expressed through a composite Coercive Leverage Index defined as the product of cost asymmetry, deniability, and normative entrapment divided by target resilience. The model holds that the coercive power of instrumentalised migration comes not from the physical size of the flow but from the gap the coercer engineers between the target's security imperative and its own legal and normative commitments to asylum and non-refoulement, a gap that converts every available response into a cost. A conceptual theory-building method is combined with a structured comparison that applies the model to the Belarus–Poland case and, illustratively, to the 2020 Turkey–European Union and 2021 Morocco–Ceuta episodes, with the index components estimated ordinally to demonstrate the model's logic rather than to measure it. The analysis finds that deniability and normative entrapment, not flow magnitude, drive the index, that the Belarusian case scores highly because it combined a deniable channel with a target deeply committed to refugee-protection norms, and that effective counter-coercion works by lowering the index, chiefly by reducing normative entrapment through lawful, legitimacy-preserving responses and by building resilience, rather than by hardening the border alone. The model offers a transferable analytic for a coercive instrument that is becoming a standard feature of grey-zone competition. All index values are model-derived and require empirical operationalisation before use.