Theologians and moralists have long attempted to restrict the use of force by states through elaborating the concept of just and unjust wars, condemning those deemed unjust. Legal efforts to outlaw recourse to war came much later, mostly dating from World War I. Until that time, international law placed certain limitations on and pre-requisites to warfare, but did not prohibit it altogether. War was still perceived as a legitimate means of achieving political objectives.

From World War I to Nuremberg

World War I ("the war to end all wars") left ten million deaths in its wake, eliminating an entire generation of young men in Europe. This catastrophe led countries to seek ways to ban war as an exercise of State sovereignty. U.S. Secretary of State Frank Kellogg, the French Minister of Foreign Affairs Aristide Briand and the German Minister of Foreign Affairs Gustav Stresemann spearheaded negotiations to conclude a treaty that would achieve this aim. On August 27, 1928, in Paris the Kellogg-Briand Pact was signed and opened for adherence by states. By virtue of Article I of this short text, the forty-five State parties "condemn recourse to war for the solution of international controversies, and renounce it, as an instrument of national policy;" in Article II they "agree that the settlement or solution of all disputes or conflicts of whatever nature or of whatever origin they may be . . . shall never be sought except by pacific means."

As a corollary to the Pact, a subsequent American Secretary of State, Henry Stimson, enunciated the doctrine of non-recognition of international territorial changes effectuated by force. This doctrine was a response to Japan's unilateral seizure of Manchuria in September 1931. The Stimson doctrine was subsequently incorporated in several international declarations, including a League of Nations resolution of March 11, 1932; the Inter-American Pact of Rio de Janeiro of October 10, 1933; and the Budapest Articles of Interpretation (September 10, 1934) of the Kellogg-Briand Pact.

Germany and Italy were among the state parties to the Pact, but this did not prevent the outbreak of World War II, in which Hitler was the principal, but not the only aggressor. The Soviet Union, for instance, joined Germany in attacking Poland in September 1939, pursuant to a secret treaty signed by foreign Ministers Ribbentrop and Molotov, in which they divided Poland between the two countries. In October 1939 the Soviet Union occupied and annexed the three Baltic States of Estonia, Latvia and Lithuania. In November 1939, it took 18,000 square miles of Finnish territory and forced 450,000 Finns to resettle elsewhere. For the latter aggression the Soviet Union was formally expelled from the League of Nations in December 1939.

Following German capitulation in May 1945, the Allies adopted the London Agreement of August 8, 1945, which contained the Charter of the Nuremberg Tribunal. Article 6(a) of this charter provided for prosecution for crimes against peace: "namely, planning, preparation, initiation or waging of a war of aggression, or a war in violation of international treaties, agreements or assurances, or participation in a Common Plan or Conspiracy for the accomplishment of any of the foregoing." Many Nazis leaders were indicted and convicted of this offence, seven of whom were sentenced to death. Despite the adherence of Germany to the Kellogg-Briand Pact, controversy emerged over whether or not the inclusion of "crimes against peace" amounted to the enunciation of new law and made the prosecutions contrary to norms of justice prohibiting punishment for offenses ex post facto. It is clear that the Kellogg-Briand Pact prohibited recourse to war, but it did not include any reference to personal responsibility or international crimes, so the issue remains subject to debate.

Whatever the legal position before the London Charter, the illegality of aggression was settled in its aftermath. By virtue of General Assembly Resolution 95(1) of December 11, 1946, the Nuremberg judgment, including the condemnation of aggression, was recognized as binding international law. At the same time, the International Law Commission was entrusted with drafting what became known as the "Nuremberg Principles," which were adopted in July 1950, and included a definition of the crime against peace.

In General Assembly Resolution 177(II) of November 21, 1947, the International Law Commission was further mandated to prepare a code on offences against the peace and security of mankind. After nearly forty years of effort, the International Law Commission adopted in 1996 a "Draft Code on Crimes Against the Peace and Security of Mankind" (not yet approved by the UN General Assembly). Article 16 of the draft code contains the following statutory definition: "An individual who, as leader or organizer, actively participates in or orders the planning, preparation, initiation or waging of aggression committed by a State shall be responsible for a crime of aggression."

Defining Aggression

General Assembly Resolution 3314 (XXIX) of December 14, 1974, constitutes the most detailed statement of the United Nations on aggression. The resolution defines aggression in its first articles. Article 1 provides:

Aggression is the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations.

Article 2 stipulates:

The first use of armed force by a State in contravention of the Charter shall constitute prima facie evidence of an act of aggression although the Security Council may, in conformity with the Charter, conclude that a determination that an act of aggression has been committed would not be justified in the light of other relevant circumstances, including the fact that the acts concerned or their consequences are not of sufficient gravity.

Article 3 lists a series of acts which, regardless of a declaration of war, would constitute aggression, including the invasion or attack by the armed forces of a state of the territory of another state, bombardment by the armed forces of a state against the territory of another state, the blockade of the ports or coasts of a state, and the sending of armed bands, groups, irregulars, or mercenaries, which carry out acts of armed force against another state.

Article 5 warns that "no consideration of whatever nature, whether political, economic, military or otherwise may serve as a justification for aggression. A war of aggression is a crime against international peace. Aggression gives rise to international responsibility. No territorial acquisition or special advantage resulting from aggression is or shall be recognized as lawful."

Article 7 explains, however, that "nothing in this declaration . . . could in any way prejudice the right to self-determination, freedom and independence, as derived from the Charter, of persons forcibly deprived of that right and referred to in the Declaration on Principles of International Law concerning Friendly Relations and Cooperation among states in accordance with the Charter of the United Nations, particularly peoples under colonial and racist regimes or other forms of alien domination, nor the right of these peoples to struggle to that end and to seek and receive support, in accordance with the principles of the Charter and in conformity with the above-mentioned Declaration."

The UN General Assembly has reaffirmed the consensus definition in several declarations, including the Declaration on International Détente (Res.32/155 (1977)) the Declaration of Societies for Life in Peace (Res. 33/73 (1978)), the Declaration on the Non-Use of Force (Res. 42/22 (1988).

UN Efforts to Combat Aggression

The United Nations was founded "to save succeeding generations from the scourge of war" (preamble), and Article 1, paragraph 1 of the Charter establishes its mandate "to maintain international peace and security, and to that end: to take effective collective measures for the prevention and removal of threats to the peace, and for the suppression of acts of aggression. . ." Article 2, paragraph 3 imposes an obligation to resolve international disputes peacefully: "All members shall settle their international disputes by peaceful means." Finally, Article 2, paragraph 4 specifically engages States to "refrain in their international relations from the threat or use of force."

The Charter prohibition of force has been repeated in countless resolutions of the Security Council and of the General Assembly. It is detailed most importantly in GA Resolution 2625 (XXV) of October 24, 1970, Resolution on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations, which solemnly proclaims that

Every State has the duty to refrain in its 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. Such a threat or use of force constitutes a violation of international law and the Charter of the United Nations and shall never be employed as a means of settling international issues. A war of aggression constitutes a crime against the peace, for which there is responsibility under international law. In accordance with the purposes and principles of the United Nations, States have the duty to refrain from propaganda for wars of aggression.

The Security Council has, however, avoided labeling breaches of the peace as acts of aggression. Even in a case as clear as the 1990 aggression toward Kuwait by Iraq, the Security Council condemned it merely as an "invasion and illegal occupation" (Res. 674/1990), and decided that "the annexation of Kuwait by Iraq under any form and whatever pretext has no legal validity, and is considered null and void" (Res. 662 (1990)). However no reference was made to the application of Article 3(a) of the definition of aggression, or to the penal consequences pursuant to Article 5.

Other uses of force since World War II could be measured against the standards laid down by the UN Charter, the Nuremberg Principles and the Declaration on the Definition of Aggression. These incidents include Dutch "police actions" in Indonesia (1947–1950), the French Indochina wars (1952–1954), the French-Algerian conflict (1954–1963), the sinking of the Greenpeace vessel "Rainbow Warrior" in Auckland Harbour in New Zealand, the war over the Belgian Congo (1960–1962), the Indian-Pakistani war 1970–1971, the Warsaw Pact's invasion of Czechoslovakia in 1968, the Soviet Union's occupation of Afghanistan in 1980, the Iraq-Iran War (1980–1990), the Turkish invasion of Cyprus in 1974 and the Vietnam War.

Justifications for the Use of Force, Self-Defense

There are, of course, some justifications for the use of force which are legitimate according to international law. Article 51 of the UN Charter stipulates: "Nothing in the present Charter shall impair the inherent right of individual or collective self-defence 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."

The application of this provision is, however, strictly limited by the over-all obligation to negotiate set forth in Article 2, paragraph 3, and the prohibition of the threat of or the use of force in Article 2, paragraph 4 of the UN Charter. In his address to the General Assembly on September 23, 2003, Secretary General Kofi Annan stated: "Article 51 of the Charter prescribes that all states, if attacked, retain the inherent right of self-defence. . . until now it has been understood that when states go beyond that, and decide to use force to deal with broader threats to international peace and security, they need the unique legitimacy provided by the United Nations." The International Court of Justice has specified the situations in which Article 51 can be invoked, most recently in an advisory opinion of July 9, 2004. The consensus of international law experts is that preventive or pre-emptive war is not compatible with article 51 of the charter, which requires an existing "armed attack" and places overall responsibility on the Security Council.

Humanitarian intervention is another possible justification for the use of force, and it remains the responsibility of the Security Council to legitimize or not a given military intervention. For example, approval was given in Resolution 688 of April 5, 1991, with respect to the necessity to create safety zones for Kurds and other minorities in Iraq. Humanitarian intervention would also have been possible in order to stop the genocide in Cambodia (1975–1979) or in Rwanda (1994).

While humanitarian intervention may be an international duty in order to stop genocide and crimes against humanity, it must not become a cloak or an excuse for military interventions responding to other political agendas. For instance, Human Rights Watch recently conducted a study of the arguments advanced by the United States as justification for the war on Iraq begun in 2003, and concluded that the U.S. intervention did not satisfy the constitutive elements of a humanitarian intervention.

Individual Responsibility

Aggression is not only an internationally wrongful act giving rise to State responsibility and the obligation to make reparation; it is also an international crime giving rise to personal criminal liability. The Diplomatic Conference of Rome adopted on July 18, 1998 the Statute of the International Criminal Court, which defines the jurisdiction of the Court in its Article 5, including with respect to the crime of aggression. Paragraph 2 of Article 5, however, stipulates: "The Court shall exercise jurisdiction over the crime of aggression once a provision is adopted in accordance with Articles 121 and 123 defining the crime and setting out the conditions under which the Court shall exercise jurisdiction with respect to this crime." This delay in the exercise of the Court's competence with regard to aggression is primarily attributable to the opposition of the United States. However, since the United States has indicated that it will not ratify the treaty, the assembly of States parties to the Rome Statute is now free to adopt a definition consistent with the judgment of the Nuremberg trials.

None of the Special Tribunals created since have jurisdiction over the crime of aggression, neither the International Tribunal for the Former Yugoslavia, nor the International Tribunal for Rwanda, nor the Iraqi Special Tribunal. Precisely because no international tribunal has been given competence to try aggressors for the crime of aggression, a number of representatives of civil society have organized "People's Tribunals."

Notable among these are the Russell Tribunal on the Vietnam War, organized by British pacifist Bertrand Russell and French philosopher Jean Paul Sartre (held 1967 in Sweden and Denmark) and the Brussels Tribunal on the Iraq War organized by former Attorney General Ramsey Clark (April 2004). The latter was conducted with the participation of two ex-United Nations humanitarian coordinators for Iraq, Dennis Halliday and Hans von Sponeck. Both tribunals condemned the United States as an aggressor in Vietnam and as an aggressor in Iraq. There is also a "Permanent People's Tribunal" (Fondation Internationale Lelio Basso), which has held more than 30 sessions, one of them in Paris in 1984, devoted to the genocide against the Armenians, and one held in Rome in 2002 devoted to international law and the new wars of aggression.

A Human Right to Peace

The international prohibition of aggression may also be viewed as asserting a human right to peace. On November 12, 1984 the United Nations General Assembly adopted Resolution 39/11, annexing the Declaration on the Right of Peoples to Peace. This declaration reaffirms that "the principal aim of the United Nations is the maintenance of international peace and security" and the "aspirations of all peoples to eradicate war from the life of mankind and, above all, to avert a world-wide nuclear catastrophe." By virtue of operative paragraph 2, the declaration proclaims that "the preservation of the right of peoples to peace and the promotion of its implementation constitute a fundamental obligation of each State." In paragraph 3, the declaration "demands that the policies of States be directed towards the elimination of the threat of war, particularly nuclear war, the renunciation of the use of force in international relations and the settlement of international disputes by peaceful means."

This declaration has been reaffirmed in resolutions of the General Assembly and of the United Nations Commission on Human Rights. In its Resolution 2002/71 of April 25, 2002, the Commission linked the right to peace with the right to development and affirmed that "all States should promote the establishment, maintenance and strengthening of international peace and security and, to that end, should do their utmost to achieve general and complete disarmament under effective international control, as well as to ensure that the resources released by effective disarmament measures are used for comprehensive development, in particular that of the developing countries." The resolution urged "the international community to devote part of the resources made available by the implementation of disarmament and arms limitation agreements to economic and social development, with a view to reducing the ever-widening gap between developed and developing countries."

In a world of weapons of mass destruction, it is imperative to strengthen the early warning and peaceful settlement mechanisms of the United Nations. In view of the human consequences of war, aggression must be prevented through international solidarity. The idea that has become the norm is that no country can take the law in its own hands. Force can only be used as a last resort and only with approval of the UN Security Council.

SEE ALSOHumanitarian Law; International Criminal Court; Peacekeeping; United Nations Security Council; War; War Crimes

Alfred de Zayas