America’s bombing of Iranian nuclear facilities has no legitimacy under international law and carries significant implications for Australia. This is especially the case given how an Israeli/American/Iranian conflict could escalate, Australia’s longstanding military alliance with the United States and the delicate current state of Australian-US relations under the Trump presidency including anxiety over Aukus. The United Nations charter recognises the right of all states to self-defence following an armed attack. However, certain conditions need to be met before a state can exercise self-defence which traditionally have been interpreted narrowly. Such an approach is essential if the UN charter prohibition on the use of force is to be maintained, and any legitimate use of military force is to be the absolute exception in the conduct of international relations. Use of force in self-defence is only permissible following an armed attack by one state against another, which has been extended to attacks from non-state actors. In this instance, there is absolutely no evidence that the United States suffered an Iranian armed attack. There have been ongoing incidents since the commencement of Israel’s 2023 military campaign in Gaza of Iranian-backed Houthi rebels attacking international shipping in the Red Sea, including US flagged shipping. Those incidents have been dealt with on a case-by-case basis and military responses have been directed at the Houthi forces. Importantly, there has been no recent attack on American-flagged shipping that could have triggered a US right of self-defence. The US since 1945 also advanced a right of anticipatory and pre-emptive self-defence. Both concepts – which are framed around notions of the imminence of an armed attack occurring – are controversial in international law, are not directly referred to in the UN charter and have never been endorsed by either the UN security council or the international court of justice. The Bush administration’s 2002 US national security strategy advanced a version of pre-emptive self-defence in direct response to non-state actors possibly acquiring weapons of mass destruction. That doctrine was developed following 9/11 in response to the emergence of the Osama bin Laden and the Islamic State group, and their possible access to Iraqi weapons of mass destruction. This doctrine was partly relied upon by the Bush administration to support its 2003 military invasion of Iraq to topple Saddam Hussein and rid Iraq of WMD. While the US did achieve regime change no WMD were ever found. The Trump administration could argue it has come to the aid of Israel through an act of collective self-defence which is recognised in Article 51 of the UN charter. There are prominent examples of such conduct such as the 1991 Gulf War when the US-led “coalition of the willing” came to the defence of Kuwait following Iraq’s 1990 invasion. However, any legal argument supporting collective self-defence must be founded on whether Israel had a right of self-defence when it launched its initial 13 June strikes on Iran. This raises similar issues to those noted above and ultimately returns to an argument of Israel seeking to exercise a version of anticipatory or pre-emptive self-defence which irrespective of the weak law on the facts is also very dubious. Legally, politically and diplomatically this places Australia in a very difficult position. Australia came to America’s military aid in 2001 following the 9/11 terrorist attacks. The Howard government famously invoked the Anzus treaty and joined in the military intervention in Afghanistan alongside the US. That was legally an example of collective self-defence that had been given implicit United Nations security council endorsement. The 2003 Australian military intervention alongside the US in Iraq was much more controversial and generated intense domestic political and legal debate. The Howard government’s legal justification was framed around United Nations security council resolutions permitting Iraqi weapons inspections and the need for Australia to join other UN members in militarily disarming Iraq. There are no such security council resolutions authorising the disarmament of Iran. In the absence of the US being the subject of an attack on its homeland and requesting Anzus alliance military support akin to 2001, it is unlikely that the Albanese government would confront the type of scenario the Howard government faced. There is a real prospect that if events in the Middle East continue to escalate and Iranian and Houthi attacks are launched against US shipping and US military assets that Australia could be asked to come to America’s military aid irrespective of any Anzus obligations. With the Albanese government remaining firm in its support of Anzus, to turn down any US request for Middle East military support could spell the death knell for not only the Anzus military alliance but also Anzus. Labor governments have a proud history of supporting the UN charter. The Albanese government consistently references its support for international law and international institutions. The US strikes on Iran require a firm Australian response supporting the rules-based international order. Any US requests for military support arising from these incidents should be declined.