Customary International Law

On 12 January 2024, the United States and its coalition partners launched a series of strikes against Houthi (Ansarallah) positions in Yemen, as part of “Operation Poseidon Archer”. Those strikes were justified as acts of individual and collective self-defence, in response to attacks by Ansarallah against civilian and naval vessels in the Red Sea. Australia provided support for these strikes; on 24 January 2024, New Zealand announced that it, too, would provide support for future strikes against Ansarallah. In this piece, I analyse whether New Zealand and Australia have become parties to a non-international armed conflict (NIAC); the legal basis underlying the use of force; and what the...