Why the Israeli Strike in Beirut and the US‑Iran Deal Raise Complex Issues of International Law on the Use of Force and Executive Authority

In a dramatic development that unfolded shortly after an Israeli military operation struck a target in Beirut, the former President of the United States publicly declared that a comprehensive agreement with the Islamic Republic of Iran had been finalized, ostensibly ending the protracted hostilities that have characterized the bilateral relationship for many years, despite the fact that the airstrike, which occurred approximately one hour before the anticipated signing of the accord, was described by the U.S. leader as a reckless and unjustified act by the Israeli Prime Minister, who was accused of acting without reasonable judgement and thereby jeopardising the delicate diplomatic choreography required for the deal, nevertheless, the parties involved proceeded with plans for the formalization of the settlement, indicating that the signature ceremony would go ahead as scheduled, while the Iranian side publicly reiterated its intention to pursue retaliatory measures in response to the Israeli operation, and the former President expressed overt anger toward the Israeli head of government, employing profane language to convey his disapproval of the strike and its perceived impact on the nascent peace process, thereby highlighting the intersection of military conduct, diplomatic negotiations, and executive rhetoric in the international arena.

One question is whether the Israeli military operation conducted against a target in Beirut can be justified under the prohibition on the use of force enshrined in Article 2(4) of the United Nations Charter, which obliges all Member States to refrain from acts of aggression unless an exception such as self‑defence is validly invoked, the answer may depend on whether Israel can demonstrate that the strike was a response to an armed attack attributable to a non‑state actor operating from Lebanese territory, thereby satisfying the necessity and immediacy requirements articulated in customary international law and the International Court of Justice jurisprudence on self‑defence.

Perhaps the more important legal issue is whether the principle of proportionality, a cornerstone of international humanitarian law, was respected in the execution of the Beirut operation, requiring an assessment of whether the anticipated military advantage outweighed the likely civilian harm, a determination that courts and tribunals typically undertake based on detailed factual inquiries, a competing view may argue that the lack of a clear and imminent threat to Israeli security renders the strike disproportionate and therefore unlawful, potentially exposing Israel to state responsibility and the obligation to provide reparations.

Another possible view is whether the United States, by announcing a finalized agreement with Iran without apparent legislative ratification, has acted within the scope of its constitutional authority to enter into international agreements, given that the Constitution assigns the power to make treaties to the President with the advice and consent of the Senate, raising a question of the legal validity of such an executive‑only pact, the safer legal position would depend upon whether the arrangement falls within the category of a political commitment that does not require Senate approval, or whether it constitutes a binding treaty that would be vulnerable to constitutional challenge for exceeding executive power.

One question is whether Iran’s stated intention to pursue retaliation in response to the Beirut strike contravenes the prohibition on the threat or use of force contained in the UN Charter, especially if the contemplated measures lack a legitimate self‑defence rationale and could be deemed an unlawful act of aggression, the legal consequence may hinge upon whether Iran can substantiate an ongoing armed attack against it that would justify a counter‑strike, and absent such justification, the international community could consider Iran’s threatened response a breach of its international obligations.

Perhaps the procedural significance lies in how any dispute arising from the strike or the US‑Iran agreement would be adjudicated before international bodies such as the International Court of Justice or through diplomatic negotiations, underscoring the importance of peaceful settlement mechanisms prescribed by the UN Charter and the Vienna Convention on the Law of Treaties, a fuller legal assessment would require clarity on the precise terms of the US‑Iran settlement, the factual circumstances of the Beirut operation, and the existence of any documented evidence of an armed attack, all of which are essential to determine the applicability of self‑defence, state responsibility, and treaty law principles.