The power of international law is severely tested when it comes to the use of force by states. The development of modern international law was spurred on by the quest to eliminate war from world politics. War in the industrial age promised to be more awful than ever before experienced by humankind. And indeed the two world wars of the twentieth century claimed countless millions of lives and left whole continents in tatters. Hence, the use of force was prohibited in the new United Nations system. This prohibition is further supported by a larger corpus of treaty and customary international law. The only exceptions permitted under the UN Charter are the use of force in self-defence, and when authorised by the United Nations Security Council (UNSC) for the purpose of protecting international peace and security. Notwithstanding this, states have continued to use force not in self-defence and without UNSC authorisation.

The use of force has been a long standing phenomenon in international relations and has been considered to be directly linked to the sovereignty of states-the limitless power wielded by states to use all possible means to guard and protect their interests. However, the longer period that war has been associated with sovereignty of state, the more the issue has turned into a legal institution by itself. This paper looks at the prohibited and permissible use of force in International Relations. Developed social awareness has expanded the limits (and even led) to the right to resort to war. This indeed has abolished the use of force or any form of threats in relation among nations, this has become a rule of law in international criminal law-its violation comes with criminal responsibility in the eyes of the international community. However, there are certain situations in which it is allowed to use force such as for self defense purposes, humanitarian intervention, and preemptive power inter alia.

In the international community, force has featured as at high levels of decentralization i.e. force has been use d for different purposes-it has been applied to previous intervention and to punish for noncompliance according to demand. War is the hardcore form of force and is used to grab territories or to completely suppress states. Reprisals are also considered as violence in international relations. Kelsen, war has been considered to be permissible due to existence of sovereignty among the states.

Prohibition to use of force and threats

The United Nations Charter in article 2(4) controls the use of force by member states. The UN Charter states that;

“All members 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.”

This law has been ratified by all the members and is protected by the United Nations Charter 1945 to prohibit the use of force by states. This was the time when Louse Doswald-Beck was the secretary general of the International Commission of Jurists  . Most scholars have interpreted Article 2(4) to be banning the use of force as in “territorial integrity or political independence of states”; the most commonly held opinion is that the above factors are only to reinforce Article 2(4)-which encompasses general prohibitions with exceptions outlined in the Charter such as self-defense and those in Chapter VII by the United Nations security council. The general principle is to ban the use of armed forces except in cases where; there is collective action-pursued to maintain or even enforce peace (Articles 24, 25, and Chapter VII) ; and Article 51which states that, “Nothing in the present Charter shall impair the inherent right to individual or collective self-defense if an armed attack occurs against a state.” In addition, other cited reasons that permit the use of force include humanitarian intervention, though this is still controversial, reprisals, and states’ protection of their nationals in other states.

The United Nations Charter and the International Military Tribunal Statute have been created with regard to international law. These laws were created by the UN member states in order to protect succeeding generations from scourges of war. Members resorted that the use of armed forces was not allowed, save in the interest of all. The UN Charter even though premising on the past is open to future amendments since the definition of the word ‘war’ has changed (and will change) over time  . One may quickly note that the word ‘war’ is not mentioned in the Charter only “force” is mentioned together with “enforcement measures”. In addition, total prohibition of use of force is not indicated since an exemption is given, “in the interest of all”. Somewhat different is the Article 2, paragraph 4, reads:

“All Members 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.”

It is quite clear that the use of force is certainly prohibited in the view of territorial integrity and independence of member states  including armed forces intervention. Thus, it is certain that the United Nations does not condone any form of reprisals, this is completely out of its purpose. The use of the term ‘force’ clearly indicates that the traditional perception on war and the modern definition are prohibited  . On that note, one can confidently argue that the United Nations Charter has surpassed previous international Acts that prohibited the use of force. Traditionally, war has been the gravest form of force. However, the view of war as an institution that permitted the attainment of state’s interests. The Charter only speaks of the use of force as legal or illegal, it does not recognize just and unjust wars, the former is a rule while the latter is an exemption.

In the eyes of most scholars, the term ‘force’ is quickly interpreted as ‘armed force’. This is a rejection of other types of force such as political and even economic. Sharmasanascvilly argues that, the different forms of force which can be used by states are prohibited as outlined in Article 2, paragraph 4 of the UN Charter. The armed forces disturb territorial integrity; however, political independence is affected in various ways

The major development in international law is the prohibition of use of threat together with the use of force itself, “threat or danger from aggression” is prohibited by the League of Nations Council (Article 10).  Thus the prohibition of threat was aimed at “”preventing and eliminating threats to peace and suppression of aggression or other breaches of peace” (Article 1, paragraph 1″  . The prohibition to use of force has been sealed by the prohibition to use threat.

Collective action

The UN Security Council is mandated to identify the existence of, and even take action to curb, any threat to peace and security among the members’ states. However, this power has not been used as expected since other measures such as the use of sanctions are taken short of the traditional armed forces by some of its members. The time that the UN used force was in 1950 to ‘force’ North Korea to withdraw from South Korea. Initially it had been envisaged by the creators of the UN Charter that the organisation would have its own forces. However, much of the command of these forces has been from the United States. The UN Security Council for also authorized the use of armed forces in 1960 during the Iraq’s invasion of Kuwait. During this time, the Council passed Resolution 678  which requested all members to support a forceful operation in collaboration with Kuwait to ensure Iraqi’s withdrawal from Kuwait. This very resolution was never revoked until 2003, when the Council passed Resolution 1441 which authorized Iraq’s invasion due to its non-compliance with the manufacture of atomic weapons-a threat to global peace and security. The UN also authorized the use of force in countries like Sierra Leone, Yugoslavia and currently Somalia.

Self defense

This is provided for in article 51. The inherent right to individual or collective self-defense in case of an armed attack allowed until the UN Security Council has intervened. The steps taken by members in the exercise of self-defense must be reported to the Security Council and must not in any way affect the mandate of the Council under the current Charter. The article states that,

“Nothing in the present Charter shall impair the inherent right of individual or collective self-defense if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by members in the exercise of this right of self-defense shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security”.

The right to self defense is still provided for in the customary international law, as seen in the International Court of Justice (ICJ), the best example is the Nicaragua Case  . Article 51 preserves the right to self defense and outlines the procedures to be followed in case of an armed attack. It has also been observed that, an irregular forceful attack can prompt the use of force as in the case of 9/11 attacks where the Security Council allowed the US to use force against the terrorists.

Pre-emptive force

The use of self defense is limited under the international customary law. The permissibility of the use of force in cases of self defense is hinged on the interpretation of Article 51. There is no right to pre-emptive self defense when an armed attack has occurred, a state does not have to wait for an armed attack to actually occur to use force. Thus, a distinction has to be drawn between, “preventive”, “anticipatory”, and “interventionary” self defense. The ICJ has not ruled out the use of pre-emptive armed force to intervene in the case of an imminent armed attack. However, opinio juris and practice widely suggest that states have no right to preventive self-defense. This can be explained well by the Caroline’s case.

Protection of nationals

Various states have asserted the controversial claim to protect their nationals abroad. This can be observed by the UK in Suez (1956), the Israelis in Entebbe-Uganda (1976), and the US force in the Dominican Republic (1965), Panama (1989), and Grenada (1983). The use of force has in some cases been linked with other political reasons beside the protection of nationals. For example, the intervention of the US in Grenada in 1983 was widely linked to the US opposition to the rising socialism in the government of Grenada. The danger posed to the US nationals in this case was not imminent and this led to strong condemnation from the United Nations General Assembly. The examples above (except for the Mossad intervention in Entebbe (1976)), the protection of nationals has been a used as a veil to cover other political agendas.

Humanitarian intervention

In modern times where terrorism has really increased, several countries are beginning to advocate for the right of humanitarian intervention without the UN’s Security Council. After the Kosovo’s crisis in 1999, countries like the UK cited the importance of the use of military force to avert such catastrophes in the future. When NATO flexed its military muscle in Yugoslavia, it had not acquired the UN Security Council’s permission. On the contrary this action was not condemned since the intervention was necessary on humanitarian grounds. Many states oppose such unauthorized intervention on legal grounds while others cite practicality-stronger nations (military wise) could misuse or overuse such powers.


The widespread debate on the significance of the article 2(4) on the use of the word ‘force’ is far much from over. The strain in opinions is where by Article 51 uses the term “armed attack” while the use of the term “force” in Article 2(4) is meant to encompass economic or other forms of coercion that are non military. Such measures are banned by other provisions. However, it does not seem to accommodate the wider definition of force. This article covers “threat of force” which is non-permissible in itself. This paper looks at such non-permissible use of force while also looking at the permissible use of force in situations such as human intervention, protection of nationals and self defense. The paper acknowledges both arguments with reference to article 2(4).