What treaties or customary international law obligations could the US have breached under Donald Trump's second term policies?

1. The UN Charter’s prohibition on the use of force: strikes, invasions and extraterritorial operations

Repeated U.S. military strikes across states (Iran, Yemen, Nigeria, Syria, Venezuela) and reported operations inside Venezuela and proposals to act unilaterally in Mexico or seize territory such as Greenland or parts of Gaza engage the UN Charter’s core prohibition on the threat or use of force absent Security Council authorization or a lawful self‑defense claim, making these acts focal points for allegations of breach of customary and treaty obligations ^{[2] [1] [4]}.

2. International humanitarian law and extrajudicial killings: civilian casualties and “targeted” strikes

Legal scholars and human‑rights groups have characterized several strikes and cross‑border actions as extrajudicial executions or unlawful under the laws of armed conflict when civilians were killed and combatant status or necessity was contested; such conduct, if established, would contravene customary IHL protections for civilians and prohibitions on summary executions ^{[3] [5] [4]}.

3. Human‑rights treaties and mass deportations, illegal arrests, and domestic actions with extraterritorial impact

Reports document mass deportations, illegal arrests, and policies that target nationals of other states, as well as cuts to refugee‑support mechanisms — actions that raise likely violations of the International Covenant on Civil and Political Rights, refugee‑protection standards, and other human‑rights obligations to which the U.S. has historically been bound or whose principles are customary, particularly where due process and non‑refoulement are implicated ^{[5] [3]}.

4. Prohibition on genocide, ethnic cleansing and population transfers: rhetoric and policy toward Gaza

Public statements and policy proposals suggesting the removal or mass displacement of Palestinians in Gaza have been cited by experts and NGOs as threats implicating the prohibition on genocide and forcible population transfer under both treaty and customary law; such claims have drawn alarm from human‑rights communities and legal commentators ^{[3] [1]}.

5. Undermining international institutions and treaty commitments: withdrawal, defunding, and sanctions

The administration’s withdrawal from or attempted exits from multiple international organizations, including UN bodies and climate institutions, and its defunding of refugee agencies, weaken treaty regimes and cooperative frameworks (such as climate accords and UN human‑rights processes) and may amount to repudiation or non‑performance of obligations the U.S. accepted in multilateral fora even if some instruments are non‑self‑executing domestically ^{[6] [7] [8]}.

6. International criminal justice and the rule of law: attacks on the ICC and cooperation norms

Sanctioning the ICC prosecutor and threatening to withdraw from judicial or investigatory mechanisms signal an effort to block accountability pathways; while the U.S. is not party to the Rome Statute, punitive measures against the ICC and refusals to cooperate contravene emerging norms of international justice and risk creating a practical breach of obligations to cooperate with certain tribunals or investigative mechanisms where treaty commitments exist ^[3].

7. Competing narratives, contested legal defences, and political agendas

The administration advances sovereignty, self‑defense, and law‑enforcement rationales for many policies — including strikes against drug cartels and unilateral measures abroad — and its supporters argue state prerogative against multilateral encumbrances; legal scholars, international bodies, and advocacy groups disagree, and several academic and professional institutions track these acts as apparent breaches or erosions of norms ^{[9] [10] [11]}. Reporting also identifies ideological and political agendas — an “America First” repositioning and conservative legal projects — that explicitly seek to scale back U.S. commitments to global institutions ^{[7] [3]}.

Conclusion: plausible breaches, contested law, and the limits of available public record

Across the documented range of actions — from military operations and alleged extrajudicial strikes to mass deportations, threats of population removal, withdrawal from multilateral regimes, and punitive steps against international prosecutors — there is a credible body of scholarly and NGO analysis arguing that the United States has likely breached or is at serious risk of breaching obligations under the UN Charter, customary IHL, foundational human‑rights and refugee norms, and norms supporting international justice; defenders point to self‑defense, domestic sovereignty, and contested legal interpretations, and public sources reflect both allegations and counterclaims, while full legal adjudication would require tribunals or state practice not yet reflected in the public record cited here ^{[1] [2] [3] [9]}.