The Mutual Assistance Clauses of the North Atlantic and EU Treaties: The Challenge of Hybrid Threats

Abstract

Mutual assistance clauses serve a dual purpose. They commit their signatories to stand up to a common threat and are thereby meant to deter potential aggressors. Their dual purpose places them at the crossroads between war and peace and the intersection between law and strategy. The rise of hybrid threats, however, has led many to question whether the mutual assistance guarantees found in the North Atlantic and EU Treaties remain suited for our present security environment. Adversaries employ tactics that increasingly seem to blur the dividing line between war and peace. The hybridization of warfare thus poses a risk that adversaries may circumvent classic security guarantees. The purpose of this Article is to compare the mutual assistance clauses of the North Atlantic and EU Treaties to determine their scope of application, clarify the nature and extent of the obligations they impose on the contracting parties, and assess their vulnerability to hybrid threats. The analysis confirms that the provisions in question are at risk of subversion, but that the impact of this threat is more limited than is often assumed. Nevertheless, this Article argues that there is no room for complacency. NATO, the EU, and their member states should take steps to strengthen legal interoperability in order to increase the legal resilience of their collective security arrangements against the challenges posed by hybrid threats.