Tacit coercion involves covert, plausibly deniable attacks below the threshold of war that signal an adversary to discreetly adjust its behaviour. Unlike traditional deterrence, which is based on clear red lines and explicit threats, tacit coercion leverages ambiguity and the implied risk of escalation. Examples including Russia’s sabotage of Baltic undersea cables and covert cyber operations illustrate how Russia communicates coercive intent yet maintains official deniability. This allows Moscow to issue warnings without triggering direct conflict, offering targets an off-ramp of inconspicuous compliance. But Western policymakers face a dilemma: they may publicly downplay such incidents while privately recognising the pattern. Over-reliance on ambiguity and off-ramps risks normalising sub-threshold aggression and emboldening it further.