Military Intervention in Syria and the “Unwilling or Unable” Test: Lawful or Unlawful?

Abstract

As is known, military intervention by the U.S.-led coalition was commenced in September 2014 in Syria. The justification invoked by some participants of the coalition was that the Syrian government was “unwilling or unable” to deal with Islamic State of Iraq and the Levant (ISIL), an international terrorist group. The “unwilling or unable” test gives rise to various debates among international scholars and practitioners. Some international publicists argue that military intervention on the basis of the “unwilling or unable” test is an emerging rule of customary international law, while others are rather opposed to it. The U.S. announced its intention to withdraw its troops from Syria on 19 December 2018. This, however, does not mean an immediate cessation of operations of the U.S.-led coalition in Syria. It is expressed in the statement made on 6 February 2019 by Mike Pompeo, the U.S. Secretary of State, in which he articulated that the arms cut in Syria is not a shift in mission but a strategic turn in essence. What can be inferred is that it seems unlikely that the military intervention of the U.S.-led coalition in Syria will be terminated in the near future. In fact, it arouses deep concern of humanity that the military intervention in Syria justified by the “unwilling or unable” test might recur in other regions or states. In this respect, the present article argues the compatibility of military intervention based on the “unwilling or unable” test proposed by some states, including the U.S., and some international publicists under universal principles of customary international law formation and international conventions.