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West Bank's 1967 Israeli invasion: does self defence justify 50+ years of occupation?

Updated: Oct 30, 2023

The 1967 Arab-Israeli conflict, better known as the ‘Six Day War’, was a fundamental turning point in the geopolitics of the Arab peninsula. Following the conflict, Israel had ‘gained territory four times its original size, and became the preeminent military power in the region’.[1]

Part of the new state of Israel included Gaza and the West Bank.[2] Many argue that the war was a preventative one; an act of pre-emptive self-defence from Israel, following the Suez crisis in 1957 and the subsequent Egyptian blockade of Israeli ships in the Straits of Tiran. However, pre-emptive self-defence is not aligned with the UN Charter, and therefore not an ‘inherent right’[3]; rather an act of aggression and an unjustifiable use of force.

While assessing Israel’s claim of self-defence, it is also imperative to analyse whether justifications of self-defence warrant a 50-year occupation of Palestine (OPT) and the legality of the current situation.

The law of self defence – Article 51 UN Charter

The current law of self-defence can trace its origins back to the 1800’s and the Caroline case.[4] That case centred around British ships in Canada (still under British rule) that had crossed the Niagara River into US territory and then attacked a ship moored on its bank, resulting in twelve people dead. Consequently, the British had argued that that was an act of self-defence.[5]

The then US Secretary of State, Daniel Webster, had outlined the three required pillars for a state to successfully argue self-defence: necessity, proportionality, and immediacy.[6] For a state to claim actions based on self-defence, there must be an ‘instant, overwhelming’[7] instance that is proportionate to the damage inflicted upon them and necessary to ensure a return to peace and stability. That was later adopted into the present-day Article 51 of the UN Charter,[8] and is now an inherent right of the members that have ratified the Charter. [9]

While the Charter places self-defence as an inherent right, there are criteria that states must meet in order to justify using this defence. First, the state must be a victim of an armed attack. The case of Nicaragua defines this as a state sending armed groups to another state and intentionally attacking them

‘to amount to’ (inter alia) an actual armed attack conducted by regular forces’.[10]

A state must be intentionally targeted. In Oil Platforms[11] no ship had been specifically aimed for in the US, and so the US had failed to meet the first criterion when arguing self-defence. Oil Platforms does develop upon the criterion of ‘armed attack’ by adding the additional nuance of severity. According to the ICJ in this case, force by way of self-defence can be used against the ’most grave forms’ of attack.[12]

In 1967, the notions of self-defence and armed attack were questioned following Israel’s justification to incite the war. In the context of the ‘Six Day War‘, Israel argued that the actions of Egypt, prior to the war, were a justification enough to act in self-defence. Israel argued, as their primary justification, that the economic blockade in the Straits of Tiran (in which 90% of their oil passes through) was a strong argument in favour of self-defence[13]. This raises the question of what, outside an armed attack, could satisfy those criteria, or whether customary and treaty law takes a more focused approach when determining a state’s right to self-defence.

The second criterion draws from the Caroline dictum of necessity, proportionality and immediacy.[14] Necessity is when a state has no other option but to enact retaliatory force against another state. It is key to note that peaceful means such as negotiation, mediation or reparations must have been exhausted before a state can resort to force.[15] Immediacy is the final pillar of the Caroline dictum; once an armed attack has occurred, retaliatory force is immediate. There are interpretive timescales for this immediacy, as it is expected that the victim state would require time to assemble both the intelligence surrounding the attack, and the proportional force to defend themselves.[16]

Proportionality requires the attack of the victim state to be proportionate to that of the perpetrator state. Retaliatory force must be proportionate to the offensive attack. This does not mean, however, that the attacks are symmetrical or identical;[17] rather that one eliminates the threat and neutralises the armed attack.[18] Proportionality also examines the weaponry used for self-defence but does not require the weaponry to be identical to the armed attack.[19]

This is where the justification of self-defence for Israel falls short as proportionality has somewhat simple criteria that need to be met. For example, in the Advisory Opinion of Nuclear Weapons, it was held that the use of nuclear weapons is never proportional to any armed attack or use of force.[20] During the ’Six Day War’, Israel’s actions were reflective of its self-defence claims. Attacks with state military against the neighbouring states, showed clear proportionality for its defence.

However, the aftermath of the war demonstrates Israel’s defence has not aligned with the above principles. From a jus ad bellum perspective, the occupation of OPT does not fall under the self-defence argument and is disproportionate to the offensive actions conducted by neighbouring states. Furthermore, the occupation of Palestinian territories Israel gained following its victory in 1967 does not meet the requirements of necessity and proportionality; an occupation of land is not necessary, nor proportionate, to an imminent/ongoing armed attack.[21]

While this is the process a state must follow when arguing self-defence per customary and treaty law, there are two other forms of self-defence states have used when justifying a use of force: the anticipatory and pre-emptive. Both have been the subject of scholarly debate as Article 51 does not compensate for these forms of self-defence. The debate for anticipatory self-defence arises when there has not yet been an armed attack, but a state believes that is it imminent. It could be due to overall tensions in a region or neighbouring states engaging in military attacks.

Those in favour of anticipatory self-defence use the Caroline dictum as further justification by stating that ‘states must be allowed to use necessary and proportionate force in order to prevent imminent armed attack on its territory’.[22] Pre-emptive self-defence is of a similar vein to anticipatory self-defence, however, the former grants states the power to use an armed attack to neutralise an emerging threat to sovereignty[23]; the attack does not have to be imminent.[24]

This, however, is out of the scope of Article 51 as it is not a state defence. For a defence to occur, an attack must have happened, and the very nature of a pre-emptive strike requires that one has not yet taken place. It is therefore arguable that this notion goes against the Charters’ guidelines of self-defence and can be perceived simply as an act of aggression.[25]

Is the current day occupation of OPT legal under the law of Self Defence?

In the aftermath of 1967, legal arguments have been raised, to determine the legality of Israel’s occupation over Palestinian territories (namely the West Bank and Gaza). The rationale behind this stems from the Israeli self-defence justification, which has allowed the further expansion of its territories.

For a state to claim self-defence for its use of force, there must be an actual or imminent attack. In the current context, Israel has conducted attacks on sites such as the Masjid Al Aqsa, by using this justification. However, it is evident that there was no actual or imminent attack in either context.[26] Israel is using the idea of pre-emptive self-defence; to use force in a bid to quash any potential attack. This alternative self-defence does not fall under the scope of Article 51 and is seen as a potential act of aggression (one of the core crimes of the Rome statute.)[27] Nasri has argued the following, supporting that:

‘Israel's recent actions constitute, under Article 147 of the Fourth Convention, as well as Article 85 of Protocol I and Article 8 of the Rome Statute, grave breaches of international law which entail individual criminal responsibility.’[28]

The West Bank and Gaza are now under the belligerent occupation of Israel and therefore governed by international humanitarian law (IHL), the area of law where, coincidentally, the rules of self-defence also operate. A fundamental tenet of belligerent occupation law is that it is temporary.[29] While international law does not have exact time frames, it is generally understood that an occupation does not last long, and that the occupying power must protect the occupied territories’ civilians.[30]

Not only this, but if occupation is taking place, there must not be any measures taken by the occupier to make the occupation permanent.[31] Attacks on Masjid Al Aqsa during Ramadan[32] and the countless other attacks on Palestinian civilians, indicate a severe lack of protection for the civilians under the occupation.[33]

Similarly, it can be argued that Israel has implemented measures that, from an outside perspective, seem permanent: for example, spousal laws between Palestinians and Israelis,[34] and the construction of a wall to create a stronger divide.[35] Taking the fundamental legal test of the reasonable person, it can be argued that a 56-year occupation of land - belligerent or otherwise - does not fit into the definition of ‘temporary’. On this note, Professor John Quigly wrote:

‘Under the UN Charter there can lawfully be no territorial gains from war, even by a state acting in self-defence. The response of other states to Israel’s occupation shows a virtually unanimous opinion that even if Israel’s action defensive, its retention of the West Bank and Gaza was not…The [UN] General Assembly characterized Israel’s occupation of the West Bank and Gaza as a denial of self-determination and hence a ‘serious and increasing threat to international peace and security.’[36]

Final Thoughts

The ‘Six Day War’ was a fundamental turning point in the geopolitics of the Middle East. The spark that started it is subject to legal controversy. The law of self-defence does not compensate for pre-emptive self-defence, as it can be easily construed as an act of aggression, providing a flimsy defence regarding the prohibition of the use of force. Thus, Israel's justification for their actions falls flat.

Even if we are to accept pre-emptive self-defence as a justification, Israel's conduct following the war showcases a state that was not a victim of force, but rather a strong, occupying power, with no intention of relinquishing its claims over the OPT. Every day that the occupation of Palestine by Israel continues, it is violating key tenets of IHL.


[1] Anver Cohen, 'The 1967 Six-Day War' (Wilson Center , 2017) <> accessed 12 June 2023. [2] Daniel L. Byman, 'The 1967 War and the birth of international terrorism' (Brookings, 30 May 2017) accessed 12 June 2023. [3] Case Concerning Military and Paramilitary Activities In and Against Nicaragua - Nicaragua v United States of America 1986 ICJ 14. [4] The Caroline v United States, 11 US 7 Cranch 496 496 (1813). [5] Ibid. [6] Hunter Miller, 'British-American Diplomacy The Caroline Case' (Yale Law School Lillian Goldman Law Library , 1934) accessed 12 June 2023. [7] Ibid. [8] Nicaragua (n3); United Nations, Charter of the United Nations, 24 October 1945, 1 UNTS XVI accessed 12 June 2023. [9] Nicaragua (n3). [10]Nicaragua (n3). [11] Case Concerning Oil Platforms (Islamic Republic of Iran v United States of America [2003] ICJ 4. [12] Ibid. Jason Blau, 'INTERNATIONAL RIGHT TO SELF-DEFENSE: THE SIX DAY WAR' (The Israel Forever Foundation) accessed 12 June 2023. [14] Caroline (n4). [15] Pukar Dahal, 'Right to Self-Defence of States under International Law: A Conceptual Understanding' [2020] 3(5) International Journal of Law Management & Humanities. [16] Ibid. [17] 'Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion' (ICJ Reports, 1996) accessed 12 June 2023. [18] Dahal (15). [19] Ibid. [20] ICJ Reports (n17). [21] Vito Todeschini, 'The (il)Legality of Israel’s Prolonged Occupation of the Palestinian Territory: Perspectives From the UN Special Rapporteur and Commission of Inquiry’s September 2022 Reports' (Opinio Juris, 7 March 2023 ) accessed 12 June 2023. [22] Dahal (15). [23] Ibid. [24] Ibid. [25] UN General Assembly, Rome Statute of the International Criminal Court (last amended 2010). [26] 'Israel/OPT: Second night of horror at al-Aqsa mosque' (Amnesty International , 6 April 2023) accessed 12 June 2023. [27] Rome Statute ICJ (n25). [28] Reza Nasri, 'Article 51: Israel's false claim' (Open Democracy , 17 February 2009 ) accessed 12 June 2023. [29] Todeschini (n21). [30] Ibid. [31] Ibid. [32] Amnesty International (n26). [33]Israel Kills Six Palestinians in Occupied West Bank, Gaza’ (Al Jazeera, 20 September 2023) accessed 24 September 2023. [34] 'Israel’s Knesset passes law barring Palestinian spouses1: Israel's false claim' (Al Jazeera, 11 March 2022) accessed 12 June 2023. [35] 'Advisory Opinion Concerning Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory', (ICJ, 9 July 2004) accessed 12 June 2023. [36] George Rishmawi, 'Was the 1967 War `“Self-Defense?'' (International Middle East Media Center, 5 June 2004) accessed 12 June 2023.

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