Hybrid Warfare, Law, and the Fulda Gap

The law constitutes an integral and critical element of hybrid warfare. Law conditions how we conceive of and conduct war. By drawing a line between war and peace and between permissible and impermissible uses of force, the international legal framework governing warfare stabilizes mutual expectations among the warring parties as to their future behavior on the battlefield. Hybrid adversaries exploit this stabilizing function of the law in order to gain a military advantage over their opponents. They do so by failing to meet the relevant normative expectations, by using a range of means, including noncompliance with the applicable rules, by instrumentalizing legal thresholds, and by taking advantage of the structural weaknesses of the international legal order, while counting upon the continued adherence of their opponents to these expectations. The overall aim of hybrid adversaries is to create and maintain an asymmetrical legal environment that favors their own operations and disadvantages those of their opponents. This poses two principal challenges, one specific and one systemic in nature. Law is a domain of warfare. Nations facing hybrid threats should therefore prepare to contest this domain and strengthen their national and collective means to do so. At the same time, the instrumentalization of law poses profound challenges to the post–Second World War international legal order. Nations committed to that order cannot afford to respond to hybrid threats by adopting the same means and methods as their hybrid adversaries without contributing to its decay.