Humanitarian Intervention and Sovereignty: Assessing the Legality of U.S. Actions in Nigeria under International Law

Abstract

This paper explores the legal implications of a potential United States military intervention in Nigeria under international law, especially considering President Trump's November 2025 threats to deploy military force to defend Nigerian Christians. The analysis assesses the proposed action against established international law principles, including Article 2(4) of the UN Charter, the Responsibility to Protect (R2P) doctrine, and customary international law related to sovereignty and non-intervention. The paper begins by establishing the factual context of Nigeria's complex security landscape, where insurgent groups, including Boko Haram and the Islamic State West Africa Province, have perpetrated violence against civilians of all faiths for over 15 years. Contrary to claims of systematic Christian persecution, empirical evidence from conflict monitoring organizations shows that both Muslims and Christians have been victims of indiscriminate attacks, with violence resulting from multiple overlapping conflicts, including jihadist insurgency and farmer-herder resource competition driven by climate change, governance failures, and economic marginalization. Through detailed analysis of relevant legal frameworks and international jurisprudence precedents, including landmark cases from the International Court of Justice and the precedents set by interventions in Kosovo and Libya, this paper concludes that unilateral U.S. military intervention in Nigeria would clearly violate international law. The proposed action cannot be justified under Article 51's self-defence exception, as no armed attack against the United States has occurred. Furthermore, it lacks authorization from the UN Security Council, which remains the only lawful mechanism for collective military action beyond self-defence. The R2P doctrine, while representing significant normative progress, explicitly requires Security Council authorization and applies only to specific mass atrocity crimes not evidently present in Nigeria's situation. Any unauthorized intervention would constitute aggression, undermining the fundamental sovereignty principles that underpin international peace and security.