1. INTRODUCTION
From the dawn of time until the end of the nineteenth century, in the international view, glory lay in whether or not a State emerged victorious from an armed conflict. Thus, it was only in the early twentieth century that a system for the maintenance of peace in international relations was formulated, which consisted of the prohibition of the use of extreme force in armed conflicts.
In this context, Article 2, paragraph 4, of the Charter of the United Nations establishes for its members that "States shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations." Along with this prohibition of the use of force, paragraph 3 of the aforementioned article subsequently introduced the obligation of States to settle international disputes by non-violent means.
However, it has become evident, especially after the Cold War, that many resolutions of the UN Security Council—created with the purpose of operating the peace-maintenance system—are not properly applied in practice and were not even drafted with a realistic scenario in mind. An example of this disconnect is that, with the fall of the Berlin Wall, the number of resolutions adopted by the Council tripled, yet without effectively contributing to the resolution of the conflict at the time.
Today's world (external link) is marked by these disconnects between theory and practice, as is visible in the wars between Russia and Ukraine and between Israel and Palestine, which, despite claiming to act in accordance with the provisions of the UN Charter, legitimize themselves through the practice of the theory of preventive self-defense. This concept is explored by researcher Torres, who establishes that this theory arbitrarily seeks to provide a justification for the domination of higher-ranking States over others, asserting the existence of a threat even though, in practice, it is neither imminent nor even real.
In her article, Piovesan (2006, p. 30) portrays the absurdity of using this theory to justify UN members initiating conflicts, stating that: if each of the 200 member States were to invoke the right to launch preventive attacks based on unilateralism, the consequences for the international order would be disastrous.
Thus, this article will analyze whether the adoption of preventive war by the United States of America violates the fundamental norms established by International Law, aiming to categorically examine this potential violation through the presentation of data produced by international legal scholars.
2. THE USE OF FORCE IN INTERNATIONAL LAW
2.1 The violation of Article 2(4) of the United Nations Charter
The theory of preventive self-defense flagrantly violates the norm prohibiting the use of force. Thus, there is an urgent need to examine what this norm is and whether it is respected in the concrete case.
This legal provision was enshrined in Article 2(4) of the United Nations Charter and prohibits the use of force against the territorial integrity or political independence of any State, being regarded by most international legal scholars as a jus cogens norm—that is, a rule that guides the values upheld by the international community, which cannot be derogated from except by another norm of the same nature that comes into existence at a later time. The Charter, therefore, as exemplified by this article, plays the important role of setting, in the interest of international security, a limit on armed actions.
This article is so fundamental to structuring world peace today that it is considered a customary norm binding on all members of the international community, whether they are signatories to the Charter or not.
Finally, the International Court of Justice, in its Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons (1996), in paragraph 47, determined that, in addition to the use of force, the very threat of using it must also be prohibited.
2.2 The exceptions: self-defense and Security Council authorization
The United Nations Charter provides for two situations in which the use of force can be authorized. The first occurs when a country is attacked first, thereby guaranteeing the fulfillment of the right to self-defense under Article 51, with the requirement that the country immediately report the action to the Security Council. The second instance covers cases in which the Council itself authorizes such use to ensure international peace. It should be noted that the article does not expressly define that the preceding attack must be armed, leaving room for unilateral and potentially harmful interpretations.
It is worth noting that, in accordance with the standards established by this body, the counterattack by the victim State must align with the principles of necessity and proportionality, aiming to curb excessive and unjustified attacks.
From this perspective, it is clear that the Council is committed to conflict resolution and forbids States from acting arbitrarily, requiring them to do so under the body's guidance. According to Volpini Silva and Rosa, this means that a State may only begin preparing militarily as a form of reprisal after the body's deliberation.
The Observatório Cosmopolita, in its report addressing the prohibition of the use of force, found approximately 433 self-defense communications submitted to the Council between 1945 and 2018, demonstrating that although in theory there appears to be a form of control and oversight over countries, in reality the Council currently accepts every action submitted as self-defense, showing that it is often more concerned with appeasing its member countries than actually restraining them.
Although the vast majority of legal doctrine regards the exercise of self-defense as valid when duly justified, it does not support using it as a justification for preventive attacks, as such action finds no basis in the procedural requirements mandated by Article 51. An example of this lack of validity is that John Yoo, legal advisor to the US Department of Justice between 2001 and 2003, went so far as to assert that the right to self-defense recognized in Article 51 of the United Nations Charter would authorize the use of force in Iraq, arguing that traditional requirements of self-defense had to be reinterpreted in the modern context of weapons of mass destruction, thus demonstrating that the justifications for the attack on Iraq stemmed from contexts created by the United States rather than being based on the express requirements of the article.
3. THE DOCTRINE OF PREVENTIVE WAR
3.1 Preventive defense as a substitute for self-defense
According to Arend, in order for a State to properly exercise the right to self-defense and have recourse to the use of force, it must demonstrate urgency and the absence of alternatives other than a counterattack against the threatening nation. However, many nations, such as the US government in its 2002 National Security Strategy, argued that preventive defense should be permitted and encouraged in situations of uncertainty and without a prior attack, merely taking into account a potential attack by adversaries, often relying on the assessment of their military capabilities and whether these were improving to the point of endangering that State's sovereignty.
Another example of such preventive action is the military attack launched by Israel against Egypt, Syria, and Jordan in the 1967 Six-Day War, in which the Israeli State carried out coordinated airstrikes in the areas of the Sinai Peninsula, the Gaza Strip, the West Bank, East Jerusalem, and the Golan Heights, in order to ensure that neighboring countries would not have the ability to threaten its sovereignty.
This preventive practice has been employed so frequently by different nations that Gray argues that, nowadays, it is difficult to distinguish whether a country truly respects Article 51 of the United Nations Charter or merely takes advantage of preventive attacks without any legal justification. However, the distinction between the two is quite clear: while an attack adhering to the provisions of the article is recognized as legal, a preventive attack is clearly a pseudo-legal pretext for aggressive war without valid justification.
Finally, it is worth noting that, in line with the findings of Bresser-Pereira (2003), the theory of preventive war has been considered illegitimate by international law scholars since its inception with the Treaty of Westphalia (1648).
3.2 The Iraq War (2003) as Proof of the Illegality of Preventive Attack
In March 2003, the United States led an invasion of Iraqi territory on the grounds that the regime possessed weapons that could threaten the international framework, while also asserting that the regime's leader was intrinsically linked to the attacks of September 11, 2001. However, these alleged weapons were never found, nor was any credible link established between the regime and the attack.
In the absence of viable justifications for this occupation of Iraqi territory, the preventive war waged there stands clearly as an ungrounded and blatantly aggressive justification. The UN Secretary-General at the time of the attack, Kofi Annan, himself stated that this invasion was not in conformity with the United Nations Charter and that, from the perspective of the Charter, it was illegal.
Prior to this war, as highlighted by Bresser-Pereira, most governments respected the Security Council's determinations; however, following this violation by the superpower, justifications for launching armed conflict grew murky and increasingly difficult to distinguish between the legality and illegality of such acts.
4. CONSEQUENCES OF PREVENTIVE WAR ON HUMAN RIGHTS
To begin exploring this topic in greater depth, it is worth clarifying the concepts of human rights and international humanitarian law, given that, although similar in phrasing, they are distinct concepts.
The Office of the United Nations High Commissioner for Human Rights (OHCHR) defines these rights as guarantees inherent to all simply by virtue of being born human beings, regardless of the religion they practice, their nationality, or their sex. Thus, the scope of human rights is specifically oriented toward protecting life, health, and dignity, applying continuously, even in peacetime.
International humanitarian law, on the other hand, is defined as a field dedicated to regulating situations arising from armed conflicts. As such, it seeks to identify ways to protect persons caught up in hostilities, for instance by creating rules that ensure humane conditions for the wounded and prisoners of war. This protection extends beyond human beings to include civilian objects located within these conflict zones, such as hospitals and homes.
Against this backdrop, their differences can be summarized as follows: while international humanitarian law comes into play only under specific conditions of armed conflict, human rights operate to protect all facets of human life. In the context of preventive war, however, both complement one another, operating in tandem to evaluate the lawfulness or unlawfulness of actions committed by States.
4.1 The Importance of the Geneva Conventions in Ensuring Respect for International Humanitarian Law
The use of preventive war as a justification, in addition to the compatibility issues with the United Nations Charter discussed above, also generated violations of jus in bello—that is, the body of law responsible for governing the conduct of States during war as well as penalizing the execution of international attacks not deemed lawful—and of jus ad bellum, which defines the lawful grounds for initiating war. These infractions constitute violations of the 1949 Geneva Conventions and of Human Rights.
First, Humanitarian Law is classified as legal protection for all peoples involved, directly or indirectly, in an armed conflict (PIOVESAN, 2013, p. 184). As such, it oversees the proper application of human rights values in areas under attack, monitoring the conduct of the States responsible for the conflict to ensure they strictly adhere to principles concerning fundamental and human rights.
For its part, the Geneva Convention specifically outlines the protection of civilians located in these war-torn territories. In accordance with Article 4 of the Fourth Geneva Convention, persons protected by the Convention are those who, at a given moment and in any manner whatsoever, find themselves, in case of a conflict or occupation, in the hands of a party to the conflict or occupying power of which they are not nationals.
At this point, it is worth emphasizing the ultimate objective of the measures adopted under international humanitarian law: formulating guidelines to strike a balance between military necessity and humanitarian requirements. This means that, when planning and carrying out attacks, armed forces must do their utmost to spare civilian lives, as well as the physical infrastructure essential to their survival.
Consequently, States have an obligation to instruct their troops in the fundamentals of international humanitarian law, punishing those who violate it and, above all, enacting legislation that more severely penalizes those who breach international provisions such as those set forth in the Geneva Conventions.
4.2 Humanitarian Consequences in Iraq
One of the primary factors behind the rising civilian death toll during the Iraq War was the use of cluster munitions by the United States—weapons that release hundreds of “submunitions” aimed at destroying multiple targets simultaneously. To give an idea of the impact, between March and April 2023, US military forces used nearly 13,000 cluster munitions containing almost 2 million submunitions, which killed or injured more than 1,000 civilians—a figure that represents only an estimate of the damage, given that to this day the exact number of people affected remains uncertain.
Data released by hospitals regarding individuals killed or admitted to their facilities during this period, reported by Human Rights Watch, reveal that records from hospitals in the cities of Hilla, Najaf, and Nasiriyah indicate there were 2,279 civilian casualties, including 678 dead and 1,601 wounded.
Another significant piece of data is that, on April 7, 2023, a “decapitation” strike was carried out—a military strategy aimed at eliminating leadership to destabilize the organization of a group or nation—which ostensibly sought to kill Iraqi dictator Saddam Hussein, but instead killed around 18 civilians and destroyed three homes in the Mansour neighborhood of Baghdad.
The report prepared by Human Rights Watch also presented evidence of violations of international humanitarian law, which included using civilians as human shields, abusing the Red Cross and Red Crescent emblems, deploying landmines in civilian-occupied territories, and placing military assets in mosques and hospitals—actions prohibited by Articles 18 and 28 of the Fourth Geneva Convention and Articles 37, 44, and 54 of the First Geneva Convention.
As highlighted by Rghebi, to this day, the Iraqi people endure the devastating consequences of the war crimes committed by the United States. Evidence of this is that, to date, civilian victims have not received proper compensation for the suffering they endured; furthermore, those who sought redress through American international courts faced institutional obstacles in addition to having their rights denied. Moreover, the strikes contributed to a lack of effective security measures in Iraq, allowing sectarian violence in the country to escalate.
Ultimately, it can be said that, 20 years after the end of the conflict, the war crimes committed by the United States remain unpunished, without any proper investigation into the extent of the human rights violations committed.
5. FINAL CONSIDERATIONS
In conclusion, the primary objective of this article was to examine whether the adoption of preventive war as a justification by States is lawful, focusing on conflicts that primarily involved the United States. From this perspective, the violation of Articles 51 and 2(4) of the United Nations Charter was also analyzed. Through an examination of legal scholarship, concrete cases, and the international legal instruments in question, it was established that a grave violation of these norms indeed exists, generating humanitarian consequences that have endured from the time they occurred to the present day.
With reference to Article 2(4) of the United Nations Charter, it has been established that it is indeed a jus cogens norm, binding on all States—even those that have not ratified it—prohibiting the use, as well as the threat, of force as a justification for initiating armed conflict. Its sole exception occurs when it is exercised due to the existence of a prior attack by another nation, which must be real and imminent; furthermore, before carrying out any retaliation, it must be reported immediately to the United Nations Security Council, conditions set forth in Article 51 of said Charter. By employing the theory of preventive war, a State flagrantly violates this article, shifting the baseline requirement of a real and imminent threat to merely a potential threat without future certainty. In this way, it transforms this normative instrument into a means of legitimizing wars of aggression.
The Iraq War, discussed in the text, serves as proof of this illegality, demonstrated by the absence of alleged weapons of mass destruction and the lack of any proven link between Saddam Hussein's regime and the September 11, 2001 attacks. Thus, it is evident that this conflict was a preventive war that failed to respect the laws contained in the international legal order. Other examples, such as the Russian-Ukrainian and Israeli-Palestinian conflicts, also fall under this concept.
In terms of Human Rights, an analysis was conducted on how the use of cluster munitions, attacks that killed countless civilians, the use of human shields, and the desecration of mosques and hospitals for military purposes constituted direct violations of the Geneva Conventions. Furthermore, through the example of the Iraq War, it is evident that the peoples who suffered from these violations still endure structural consequences today, alongside a lack of compensation for the moral and material damages they suffered.
The statement made by Piovesan (2006) remains timely and valid:
If each of the States that make up the international order can unilaterally invoke the right to preventive attack, the entire legal architecture built after the Second World War will be hollowed out.
Thus, if the Security Council effectively puts into practice the prohibition on the use of force and punishes those who violate it, it can be considered a true guardian of peace, moving beyond the current perception that it is merely a body that ratifies the will of its most powerful members.
Finally, it is concluded that preventive war is illegal from the standpoint of current International Law. Overcoming it requires not only strengthening international punitive mechanisms, but also joint efforts among nations so that humanitarian values are prioritized over any type of conflict between States that might escalate into armed war. This will ensure that the prohibition on the use of force becomes effective rather than remaining a mere theoretical norm lacking concrete application.