Rethinking International Law After Gaza Symposium: Unlawful Occupation as Ongoing Aggression – Rethinking Legal Responses in the Context of Palestine*

Written by: Ihsan Adel, Founder and Chair of Law for Palestine and an international lawyer currently pursuing a PhD in Germany.

The Israeli occupation of Palestine has long tested the limits and efficacy of international law. However, recent legal developments, particularly the ICJ’s advisory opinion, have intensified the call to recognise this occupation not only as an illegal act but as an outright form of aggression. This marks a significant turning point. The prohibition of aggression lies at the core of the international legal order established after the World Wars; committing it constitutes one of the most egregious violations of the global order, threatening international peace and security, and bringing with it individual criminal responsibility. As such, international law demands an immediate, collective, and decisive response. Yet, despite overwhelming evidence of Israeli aggression, the international legal community has been slow -dangerously so- to recognise and act upon this crime.

This delay has had catastrophic consequences. The ongoing occupation, now extending over decades, has not only inflicted immense suffering but has also repeatedly undermined international peace and security. The recent conflagration in Gaza and the wider region is a direct outcome of this failure. Had the international community acted decisively, applying international law effectively and with urgency, much of the bloodshed could have been prevented. Tragically, this failure persists, even two months after the ICJ’s advisory opinion. As 39 UN experts have warned, “the edifice of international law stands upon a knife’s edge”. Reinvigorating international law -and critically rethinking its application- must be at the heart of our discourse. This rethinking must extend beyond legal interpretation to encompass the mechanisms and processes used to enforce international law.

The Nexus Between Unlawful Israeli Occupation and Aggression: Revisiting the ICJ’s Findings

The ICJ’s advisory opinion on the unlawfulness of Israeli occupation of Palestine presents a compelling case for recognising this occupation as an act of aggression. The Court emphasised that occupation inherently involves the continuous use of force in foreign territory, governed by jus ad bellum-the body of international law that governs the legality of the use of force. This conclusion is critical. Under the United Nations General Assembly’s (UNGA) definition of aggression and Article 8 bis of the Rome Statute, any unlawful use of force, including illegal occupation and annexation, constitutes aggression.

The ICJ unequivocally stated that any exercise of effective control by an occupying power must adhere to the prohibition on the use or threat of force. A breach of this principle constitutes an act of aggression. According to the Court, Israel’s ongoing annexation of Palestinian territory, its assertion of permanent control, and its obstruction of Palestinian self-determination violate fundamental tenets of international law, exceeding the bounds of mere occupation, rendering Israel’s presence in Palestine unlawful. The ICJ also concluded that these actions contravene the prohibition on the use of force in international relations and the principle of non-acquisition of territory by force. Such violations directly breach Article 2(4) of the United Nations Charter, which explicitly prohibits the threat or use of force against the territorial integrity or political independence of any state. Although the Court refrained from explicitly labelling the Israeli occupation as aggression, its conclusions on the illegal occupation align with the legal definition of aggression under international law.

Why Has the ICJ Avoided the Term ‘Aggression’?

The implicit indication of Israel’s actions constituting aggression is a label the Court and other UN bodies have long been reluctant to adopt, largely due to the significant political ramifications. However, numerous states and organisations -including Namibia, the League of Arab States, Lebanon, Algeria, and Palestine- have argued in their submissions to the Court that the ongoing Israeli occupation constitutes a form of aggression. Additionally, UN Special Rapporteur Francesca Albanese has called for a ‘paradigm shift,’ asserting that the occupation is ‘an intentionally acquisitive’ endeavour, entailing an unlawful use of force, and can thus be seen as an act of aggression.

UN Special Rapporteur Francesca Albanese has called for a ‘paradigm shift,’ asserting that the occupation is ‘an intentionally acquisitive’ endeavour, entailing an unlawful use of force, and can thus be seen as an act of aggression

The ICJ’s cautious approach is not unprecedented. Despite the clear parallels between illegal occupation and aggression, the Court has consistently been cautious in applying the term “aggression” in its rulings. To date, it has never explicitly used the term to describe the actions of any state. This reluctance likely stems from the Court’s traditional role in adjudicating state disputes, thus avoiding the need to engage with the definition and criteria of aggression, which ultimately leads to individual criminal responsibility. Moreover, it may reflect the principle of judicial economy, as the legal framework governing the use of force -enshrined in Article 2(4) and Article 51 of the UN Charter- and the jus cogens norms of international law, are more firmly established.

Nevertheless, the ICJ has often invoked the concepts of unlawful “use of force” and “aggression” interchangeably in its opinions, frequently referencing General Assembly Resolution 3314 on the Definition of Aggression and other key legal instruments to guide its judgments. For instance, in the case of Uganda’s occupation of parts of the Democratic Republic of Congo (DRC), the ICJ avoided directly labelling Uganda’s actions as aggression. However, it extensively cited the definition of aggression to describe Uganda’s violation of international law, particularly its infringement on the DRC’s territorial integrity and its unlawful use of force during the occupation of Ituri. Several judges, in their separate opinions, explicitly characterised Uganda’s actions as aggression, underscoring the legal connection between illegal occupation and aggression.

The ICJ tends to frame violations of sovereignty and the illegal use of force in broader terms, avoiding direct references to the crime of aggression. However, this cautious approach is becoming increasingly unsustainable in light of the situation in Palestine, where the international legal system’s failure to act decisively risks rendering its principles meaningless.

The UN Security Council and General Assembly’s Approach to Aggression

Notably, the Security Council has similarly been reluctant to invoke the term “aggression” in certain contexts. For instance, during Uganda’s occupation of the DRC, the Council copied the definition of aggression when condemning Uganda’s unlawful occupation and its illegal use of force but refrained from explicitly labelling it aggression. By contrast, in South Africa’s 1976 invasion of Angola, the Security Council swiftly identified the violation of sovereignty and territorial integrity as an act of aggression, underscoring the political factors that influence the use of this term in international discourse.

In contrast, the General Assembly has often been more assertive in its application of the term. It designated several occupations, including South Africa’s occupation of Namibia, Portugal’s occupation of Guinea-Bissau, and the Russian invasion of Ukraine, as acts of aggression. Notably, during the 1980s, the General Assembly condemned Israel’s occupation of Arab territories as aggression, demanding Israel’s immediate and unconditional withdrawal (a categorisation that has not been used in the context of Palestine since, particularly following the initiation of the so-called peace process, which has failed dramatically).

Based on previous General Assembly resolutions, three conditions can be identified for determining when an occupation constitutes aggression:

1. Violation of Territorial Integrity and Sovereignty: The occupation must breach the territorial integrity, political independence, and sovereignty of the occupied state.
2. Denial of Self-Determination: The occupation must deny or obstruct the right to self-determination of the people under occupation.
3. Hostile and Unprovoked Nature: The scale and severity of the ongoing presence in the occupied territory are both hostile and unprovoked, marked by, for instance, claims of a permanent foreign occupation, widespread loss of life, extensive destruction of property, or the displacement of vast numbers of refugees.

These conditions are clearly fulfilled in the case of Israel’s occupation of Palestine, since its inception and perhaps now more than ever. The ICJ’s advisory opinion recognised the violation of Palestinian sovereignty, the denial of their right to self-determination, and the ongoing annexation of Palestinian land -acts that fulfil the criteria for aggression under the General Assembly’s definition (Even if the initial occupation in 1967 was allegedly legitimate as a response to a security threat, its continued nature, in violation of international law and Palestinian self-determination, as the ICJ concluded, now constitutes illegal use of force, i.e. aggression).

The Critical Need for Timely Legal Action

The failure of the international legal system, especially states at the UNSC and the UNGA, to acknowledge this as an on-going aggression and enforce the rule of law has allowed the aggression to fester. Decades of inaction have allowed Israel to further entrench its occupation, solidify its control over Palestinian land, and systematically violate the Palestinian people’s right to self-determination. The ICJ’s advisory opinion on Palestine, while cautious, points towards the Israeli occupation as a form of aggression and this characterisation has far-reaching implications. Under international law, aggression is a breach of the core principle on which the post World War II legal order rests, and hence cannot be justified by security concerns. It constitutes an illegitimate and unjustified use of force, and the global community must recognise this legal reality and respond accordingly. If this situation continues, particularly in light of the ICJ’s advisory opinion and the UNGA Resolution, it poses a threat not only to the Palestinian people but also to the foundations and integrity of the international legal system itself.

Today, the international community’s failure to act swiftly and decisively against the occupation has allowed the conflict to evolve into a broader regional crisis. The ongoing violence across the Middle East can be traced directly to this initial failure to confront Israeli aggression with the response it necessitates as per international law. Furthermore, the states parties inactions have eroded democratic values, as the growing divide between public opinion and government policy, along with the suppression of dissenting voices, becomes ever more apparent on the streets and university campuses of Europe and the United States. Had the international legal community acted when it was supposed to, much of the violence, including the recent Gaza genocide, could have been prevented. This represents not merely a theoretical failure of international law but a practical failure to apply the law effectively and in a timely manner.

When the General Assembly acknowledged this legal and factual reality in the 1980s, recognising the Israeli occupation as an act of aggression, it had significant implications -albeit largely theoretical at the time- when it followed this classification with a call for action

When the General Assembly acknowledged this legal and factual reality in the 1980s, recognising the Israeli occupation as an act of aggression, it had significant implications -albeit largely theoretical at the time- when it followed this classification with a call for action. In Resolution 38/180A (1983), the Assembly condemned any political, economic, or military support that enabled Israel to perpetuate its occupation and acts of aggression. The resolution called for the suspension of military assistance to Israel and the severance of diplomatic, economic, cultural, and technological relations. Today, thirty years later, in light of the ICJ’s advisory opinion, the international community has reiterated these recommendations through a new UNGA resolution, demanding measures to halt the illegal occupation, which is, in essence, an act of aggression, albeit without explicitly labelling it as such. The mistakes of non-compliance must not be repeated, and the stalemate that has persisted since the 1980s, in light of ongoing aggression, must not be allowed to resurface.

Rethinking International Law: A Call for Action

This brings us to a crucial juncture: the urgent need to rethink the application of international law in cases of aggression and illegal occupation. It should not require decades or the immense loss of life for acts of aggression to be recognised and addressed. The Israeli occupation has endured for far too long, shielded by a legal framework that is wilfully slow to act and hesitant to confront powerful actors.

To address this, the international community must develop mechanisms that ensure a more rapid and decisive response to aggression. First, the legal community must adopt a proactive stance, recognising prolonged occupation as aggression, especially when it entails systematic violations of sovereignty and self-determination. Second, international bodies such as the General Assembly -while acknowledging the limitations of the Security Council due to its self-imposed veto- must take swift and decisive action in such circumstances, holding aggressor states accountable without undue delay, including through the ICJ, as evidenced by its recent advisory opinion. International legal proceedings should no longer be impeded by geopolitical concerns.

In addition to recognising the status of an unlawful occupier as an aggressor, it is imperative to acknowledge that the struggle and resistance of the people under this occupation, insofar as it adheres to the applicable rules of international law, is legitimate. The persecution of such resistance by the occupying forces must be unequivocally rejected -as the General Assembly affirmed in the 1970s and 1980s. Moreover, issuing illusory calls for negotiations between the parties only serves to legitimise the illegal aggression. Instead, the focus must be on the immediate withdrawal and the unequivocal end of the aggression and illegal occupation.

Under the ICJ advisory opinion (para. 274) and the rules of the Responsibility of States for Internationally Wrongful Acts, the unlawful use of force constitutes a violation erga omnes, signifying that states bear an obligation to act, including unilaterally and through regional groups and institutions, to prevent the continuation of aggression. This necessitates concrete measures, inter alia, the imposition of targeted sanctions, the severance of diplomatic relations, and the invocation of universal jurisdiction for crimes of aggression, ensuring that states cannot evade accountability through political influence. Furthermore, states must ensure accountability at the national level, holding their citizens and businesses responsible for aiding aggression, whether by serving in the occupying army or engaging in activities that enable the continuation of the illegal occupation. This obligation aligns with the UN General Assembly’s recent resolution on Palestine, which rightly recommended such measures to halt the ongoing aggression.

States bear an obligation to act, including unilaterally and through regional groups and institutions, to prevent the continuation of aggression

The role of local, regional, and international civil society and academic institutes is vital in this regard. As Richard Falk aptly described, there is a need for a “militant form of solidarity” or “militant activism” to cultivate the political will among nations to mount an effective challenge.

Conclusion

The Israeli occupation of Palestine stands as one of the most egregious examples of prolonged aggression in modern history. The ICJ’s advisory opinion brings us closer to recognising this occupation for what it is, a continuous act of aggression, but the international legal community must go further. We need a rethinking of international law that prioritises timely responses to aggression, ensuring that no state, no matter how powerful, can commit acts of aggression without facing legal consequences.

The lesson from Gaza and the broader region is clear: delayed justice is no justice at all. The failure to halt Israeli aggression in Palestine has not only prolonged the suffering of the Palestinian people but has also sown the seeds of destruction for the entire international legal order. The time for rethinking, and indeed, for decisive action, is now.

* This blog was first published by Opinio Juris. Law for Palestine republishes it here with the permission of the blog and the author.