Trading limited blows: the effect of counter-hassling on deterrence stability in the gray zone

Gray zone challenges, status quo-altering actions below the threshold of military aggression, are on the rise. One popular deterrence strategy for defenders is to ‘hassle’ with limited but punitive responses and force challengers to either escalate or back down. But what happens when challengers have a third option to ‘counter-hassle’ and trade limited blows with defenders? State-of-the-art deterrence scholarship has yet to directly address this question. This article uses formal modeling to pinpoint two direct effects on deterrence dynamics: challenger counter-hassling capacity 1) shifts the burden of escalation back onto the defender, and 2) drives up the defender’s threshold beyond which hassling is profitable. As a result, challengers are encouraged to undertake more frequent and more demanding challenges when they have a counter-hassle option. To illustrate this finding in practice, the article links observable intensification of Chinese gray zone activity in the South China Sea region to its targeted cultivation of counter-hassle capacity.