This short note considers the Attorney General’s maximalist approach to international law in the context of the advice he is reported to have given about the lawfulness of UK military action in support of Israel against Iran. The Attorney’s advice may result in the UK Government obstructing US military action against Iran insofar as those operations rely on the joint base in Diego Garcia.  The new agreement between the UK and Mauritius, which has yet to be ratified, introduces new legal risks to the future use of Diego Garcia, including (1) the risk that Mauritius may take counter-measures in response to military action that it thinks is unlawful and (2) the risk that Mauritius demands prior notice of military operations.  The Attorney’s approach to international law threatens to compound these risks to UK security interests and to our alliance with the United States.