Vital Interests: In this forum, we are talking about issues of concern for the United States and topics on which we think people should be informed. The use of force is an important aspect of state power but  is not clear in today’s context when and how the United States or global powers can exercise this capability. Could you provide an overview of how the rules and norms on the use of force have evolved and are currently considered?

Mary Ellen O'Connell: This is clearly an important topic.  The global community has seen so much violent conflict in the last 30 years, while states show declining regard for the international law that restricts it. People seem no longer aware of the relevant law and no longer demand that their governments comply. This is a change from attitudes at the end of the Cold War.

One of my personal hopes for the coming U.S. presidential election in the United States is that new or re-elected current leaders will understand the importance of this law and recommit the United States to it. I am referring to the international law that governs the resort to military force. Other international law regulates the conduct of armed conflict, but let’s focus on resort to force here. 

The 1945 United Nations Charter codified an ancient legal and moral principle prohibiting the resort to war for any but a very few reasons. The prohibition has been part of international law since modern international law arose with the emergence of the state system in 1648. Prohibiting force and intervention were essential to the move away from the imperial system of the Holy Roman Empire to that of legal, co-equal sovereign states. The architects of the new system incorporated the ancient principles into the new system of inter-state law.  

After two world wars in the 20th century, national leaders moved to commit the prohibition on force to a multilateral treaty that also established an organization to support it. The United Nations Charter begins with the line, "We, the peoples of the United Nations, to save succeeding generations from the scourge of war, unite..." The whole purpose of the UN is to eliminate war--”armed conflict” as it's called in the Charter, and to prevent the vast suffering that people experienced in World Wars I and II.

Chapter I of the Charter is all about committing to international law. Article 2(4) of Chapter I prohibits the use of force by one sovereign state against another. The United Nations International Court of Justice has ruled in a number of cases on the proper interpretation of the Charter principles relating to the use of force as well as principles found in general international law outside the Charter. For example, the Court has indicated that low levels of force fall below the Article 2(4) threshold. Such uses may still violate international law, such as the principle of non-intervention, but not Article 2(4). Lesser border skirmishes or the use of force in law enforcement  come under different rules. 

With respect to Article 2(4), there are are two exceptions to the prohibition in the Charter and one possible exception outside of the Charter. The initial drafts of the Charter had only one exception. That was for the United Nations Security Council to authorize force when the Council determined that using force against a state that might break the rules and violate the prohibition on the use of force. The Security Council could organize a counterforce to restore the situation prior to the violation of Article 2(4).

At the last minute during the final negotiating conference, Latin American countries wanted a specific provision devoted to self-defense. They wanted a clarification that if a state was attacked, it could defend itself and request the assistance of other states in “collective self-defense”.  They wanted to establish a regional organization that would support collective self-defense, so that if one state was attacked, the others would be ready to come to its assistance. To provide for collective self-defense, the Charter drafters included Article 51:

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. Measures taken by members in the exercise of this right of self-defence 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 provision is very narrow. It is intended for an emergency situation and to trigger collective self-defense rights. NATO, too, was founded as a collective self-defense organization. The third exception from outside the Charter, is, in my view, controversial. It is consent. Governments the world over invite states to use military force in their territory when facing armed insurrection. It is a problematic concept, often leading to  excessive use of military force in situations where principles of self-determination, human rights, and so on would restrict military force. 

All of this international law was well understood before the end of the Cold War in 1989. The Soviet Union and the United States were holding each other to the actual words of the Charter. When the Cold War ended and the U.S. was no longer being held to a rigorous interpretation of the Charter, we began to see uses of military force inconsistent with the Charter’s terms. 

This trend away from the law has continued throughout the post-Cold War period so that states are now asserting that they can use military force in human rights or governance crises, for arms control, to attack people suspected of terrorism, or even to execute individuals suspected of planning future crimes. These new purposes explain why there is so much unlawful resort to military force in the world today.

VI: To go back to the origins of the Charter and the start of the Cold War, would you characterize the outbreak of conflict in Korea in 1950 as an early test of the principles prohibiting the use of force? There was reluctance to call the military action in Korea a war,  at the time it was labeled a UN “police action.” 

Mary Ellen O’Connell: The Korea case is very complicated. The facts are worth reviewing for a moment because, as you suggest, it was a major test.  Let me go back a little earlier than Korea to earlier tests when the UN system was quite successful. The Security Council supported truce observer missions in the India-Pakistan conflict and also in the Middle East. The first actions by the Security Council were low-level but effective in supporting ceasefires and de-escalations of armed conflicts there.

We then had the complicated, post-Second World War situation on the Korean Peninsula in which the United States and the Soviet Union were already showing their willingness to compete militarily for territorial control in strategic areas of the world. Each rushed troops to the peninsula as the Japanese retreated. Both the Soviet Union and the United States wanted to insert their own troops to ensure their influence in the power vacuum.

This was a replay of what we saw in Germany and in Eastern Europe and Western Europe between the U.S. and the Soviet Union. Korea, a much smaller country, was  effectively divided as a result of the competition. North Koreans, at the instigation of the Soviets or the Chinese attacked across the 38th Parallel being observed as the de facto line between the Soviet Union and the United States.

When North Korea crossed to the south, the Security Council debated a response but in the absence of the Soviet Union, which was boycotting to pressure the Council to recognize the Chinese Communists as the rightful holder of China’s permanent member seat over the Chinese Nationalists. In the absence of the Soviet Union, the U.S. was able to get an authorization to use military force to push the North Koreans back across the line. It was, I now believe, an unfortunate decision. It put the UN on a wrong track about authorizing military force. The Soviets were taking the correct position that the authorization needed the affirmative vote in favor, against or to abstain. Absence is not an affirmative vote. 

It really caused one of the ongoing problems of the Security Council, which is that the Council members, the permanent members, believe they can veto anything, any decision, not to be reserved for substantive decisions as was the original intent of granting this critical veto power. The U.S. led the Council into a highly questionable resolution in favor of force, instead of crafting the non-military solutions to crisis that the UN was founded to support. Korea remains a divided peninsula and place where the risk of catastrophic war is a daily reality.

But, perhaps surprisingly, the UN survived the Korea crisis, and the Secretary General and UN General Assembly created the institution known as Peacekeeping. UN Peacekeeping during the Cold War succeeded in its 17 missions. Unfortunately, with the end of the Cold War, Peacekeeping changed from keeping the peace to attempting to enforce it. That has not worked. The UN today is in greater danger of irrelevance than at any time since 1945. 

VI: Korea is  one example of the use of armed force in the Cold War. What about the colonial wars that took place in the years after the Charter was adopted? There were armed battles by colonial powers trying to maintain their colonies in Africa and Asia. The French military involvement in Indochina, now Vietnam, was taken up by the United States and justified as an “allied” effort to stem the spread of communism. Did the UN Charter also fail in this context?

fMary Ellen O’Connell: Those were painful conflicts. In addition to Indochina, the French fought a very tough imperial war in Algeria. The Portuguese fought to hold on to their colonies in Africa--Mozambique and Angola. The United States basically took up the French position in Vietnam when France lost the battle of Dien Bien Phu. The UN Charter clearly supports self-determination. The United States wanted the UN to take a stand against colonialism.

Unfortunately, the Cold War led U.S. presidents to prioritize opposing communism over supporting an end of colonialism and self determination. They sided with the French against the nationalists in Vietnam. The U.S. also went to great lengths to attempt a legal justification for its intervention that would be consistent with the Charter. The U.S. insisted that Vietnam was two sovereign states, North and South, and that the South had invited the U.S. to join in its defense against the North that had attacked it unlawfully. The U.S. cited Charter Article 51 and the right to use force in collective self-defense.

The U.S.’s manipulation of the facts to meet the legal test is like the U.S. policy in Vietnam of destroying villages to save them. The U.S. would have been on stronger legal grounds to argue the Charter does not clearly prohibit assistance to colonial powers seeking to end insurgencies. The colonial powers took the view that these wars were internal affairs and that the Charter does not apply to internal affairs and that even the Security Council is barred from authorizing external involvement in civil wars.

When I say that the post-Cold War period has been more challenging to the international law restricting the use of force, I don't mean to say that the Cold War was not a time of great violence. Korea, the colonial wars, and the proxy wars all prove otherwises, but it is accurate to say that there was more fidelity to the actual terms of the Charter during the Cold War. The Charter set mutually agreed and respected legal rules on resort to force. 

When the Soviets invaded Hungary, when the U.S. went to war in Vietnam, they cited valid legal justifications. The facts did not fit those justifications and the interventions were unlawful, but the law remained in-tact. Other governments and scholars could build the case for respect for law on a firm base.

The difference now is that governments of states with major military forces are manipulating the law.  They have, until the era of Putin, Trump, and Xi, at least cared about having a legal justification. When the Cold War ended government lawyers began characterizing not the facts, but the law to fit policy. President Trump has been particularly egregious, only citing the Charter when under great pressure following the assassination of General Quassem Soleimani on January 3, 2020, because of the extreme nature of the departure from even the weak Obama administration justifications for targeted killing.

In Syria the Assad government, that is in effective control, invited assistance from Russia and Iran, but not from the United States, France, Great Britain, Israel, or Turkey, and yet those countries are acting as if there is no rule stopping them them using military force on Syrian territory.

VI: Recently, there has been  another example in Libya where the UN-recognized national government holding on in Tripoli is inviting in Turkey to fight against an insurgency that is supported by the Russians. If Turkey sends troops into Libya, is that a justified use of force?

Mary Ellen O’Connell: What you’ve just described is the very type of chaotic situation that has emerged since 1989. Outside intervention in Libya since 2011 has only led to greater conflict. In my view, no outside states have the legal right to accept any invitation to intervene in Libya as of early 2020. It is a situation where the weakness of the UN is palpable. Before the end of the Cold War, we would have expected the UN Secretary General to organize mediation among the conflict groups to win a cease-fire. At that point, UN Peacekeeping troops could support the cease-fire until a government of national reconciliation could be established. The UN is failing in Libya as in so many other places and senseless military force is winning.

VI: To focus a little bit on the United States, its declaration of the Global War on Terror provided a whole new avenue for using force against non-state actors anywhere in the world. That opened up the entire world for the United States to use force wherever it saw threats from any kind of terrorist entity. The idea was to get them out there, before that they could attack the Homeland. That has resulted in horrendous realities in Iraq, the ongoing situation in Afghanistan and now special forces and drone attacks throughout Africa. Is the  Authorization of Use of Military Force, the AUMF, a valid methodology for the United States to use?

Mary Ellen O’Connell: The Authorization for the Use of Military Force, which was adopted after the 9/11 terrorist attacks in the United States, is a doctrine of U.S. domestic law. It is supposed to honor the U.S. constitutional obligation that declarations of war, decisions to resort to war, must be made by the Congress and the President acting together. We have not formally declared war since the Second World War after the Pearl Harbor attacks in terms of United States domestic law.

There's been increasing concern that the U.S. constitutional restrictions on the president just going to war on his own are virtually gone. The one attempt to put some Congressional power back behind these very important decisions by the government was first the War Powers Act of 1973, in discussion again following the Soleimani assassination, and Authorizations for the Use of Military Force against Al Qaeda and associated forces, as well as against Iraq. 

International law is part of the law of the United States. Any AUMF should be read as Congressional support for presidential uses of force that are lawful, which means under international law and purely domestic law. U.S. presidents are violating international law and Congress should hold the president to account in the only way it can, by ending funding for unlawful wars and uses of force by whatever name--targeting killing, intervention by invitation, pro-democracy, anti-atrocity, punishment for chemical weapons use, or nuclear non-proliferation. When Congress cut funds for the war in Vietnam, President Nixon finally withdrew U.S. forces.

By now Congress should realize that the unlawful use of military force is a waste of lives and money. Trillions of dollars have been spent since 9/11, yet, Al Qaeda still exists and inspires new, more diabolical organizations, such as ISIS. If we have a problem with Al-Shabaab in Somalia, we should be working for decent government in Somalia. Instead, U.S. presidents just keep undermining stability by using military force without coordination or respect for civil society. U.S. military force in Yemen since 2002 helped to destabilize that country. Saudi Arabia with U.S. assistance has intervened in the resulting civil war in 2015, with catastrophic effects for the civilian population. Tragically, there are more examples.

VI: Is there censure? Is there pushback by the United Nations in any form at all to this kind of arbitrary use of force by the United States?

Mary Ellen O’Connell: As I indicated, the UN is not living up to its promise. The UN Human Rights Council and other UN human rights bodies have sent special rapporteurs to investigate U.S. drone strikes. The very first U.S. drone strike outside of an armed conflict zone (or “hot battlefield” to use an Obama administration term) was in Yemen in 2002. The UN Special Rapporteur, Asma Jahangir, issued a report in January 2003 stating authoritatively that the drone attack that killed six people, including a 23-year old American was an extrajudicial killing, not a justifiable use of military force in self-defense.

In my view, subsequent special rapporteurs attempted to include government references to the international law on the use of force. They have given some credibility to legal doctrines that began the slide away from the terms of the UN Charter. Jahangir, in my view, was absolutely right. When using military force outside an armed conflict zone to intentionally kill is unlawful. 

The whole consensus around the rules on the use of force as stated in the UN Charter  has been eroding. Yet, this law defends human rights and needs the support of human rights defenders. They can cite a very important document agreed to in September 2005, in the wake of the U.S.-led invasion of Iraq in 2003. The World Summit Outcome document is the conclusion of a thorough assessment of the Charter law on the use of force.  Every UN member agreed that the Charter rules as written require strict compliance. That is the word the document uses, "strictly." 

VI: Related to this reluctance to condemn the use of force, we also see an  abrogation of disarmament treaties and the virtual arming of the world. The arms trade has never been more active in not just conventional weapons, but also a new generation of autonomous weapons like drones that are in development and certainly will be operational very soon. 

Mary Ellen O’Connell: You describe a dangerous reality. There is also more and more interest in nuclear weapons because they are perceived to be the only way for a state to prevent military intervention by states with nuclear weapons. In early 2019, two nuclear-armed states, Pakistan and India, carried out military attacks on each other. At this dangerous moment, the Presidents of China, Russia, and the U.S. are either refusing to join new arms control treaties or are abandoning existing ones.  The focus is on material gain -- selling military hardware and making money, not the law. 

VI: It seems to be following a disturbing adage that might makes right?

Mary Ellen O’Connell: It is a return to the thinking of Realism that fueled the Cold War. Weapons manufacturers promote this thinking. They want the profits generated by devoting resources disproportionately to the military, starving diplomacy and international institutions devoted to peace through law. And, of course, weapons need to be used so they can be replaced. The only game in town seems to be the constant resort to military force. 

The U.S. and other states are spending huge sums to create autonomous weapons that will use artificial intelligence, machine learning, to select and destroy targets without human intervention.  Presumably the targets will change as the algorithms dictate. Soon there will be the ability to kill people in very large numbers without any individual accountability. Fleets of small killing machines may replicate the devastation of a major plague. When the world is awash with such violence, the legal concept of killing in an armed conflict versus peace will become meaningless. It will be a world of ubiquitous, seemingly random, violence.

The world may resemble the end of the Roman Empire with all kinds of marauding gangs or Europe during the Black Death when one in four persons died. The law is the only tool to hinder this possibility. We can ban autonomous and other highly destructive weapons. More emphatically, we can resurrect the prohibition on the use of military force. We can strengthen the norm against killing in favor of the human right to life.

VI: Thank you for this enlightening and sobering discussion on the realities of the use of force in the world today. Let’s hope 2020 candidates and the public understand the urgency of considering the importance of international law and the rules it has taken generations to foster.

Mary Ellen O’Connell: Following the U.S.-Iran crisis at the start of January 2020, I expect Democratic candidates to finally turn to foreign policy. There has been some discussion to date of “ending the endless wars”, in particular of the 18-year war in Afghanistan. The candidates have said little about the U.S. role in Yemen. Congress did try to pass a bi-partisan resolution for the U.S. to end its military force in Yemen. The president paid no attention to it. 

What good does it do to try to create prosperity, protect the environment, and provide a decent health and education system in the United States if the basic rules of the international community are being crushed? 

My last thought is a positive one, that one of the lessons of history is that as human beings we do fundamentally and deeply understand the importance of peace and law.  I am confident, if it is not during this election, it will be the next election in which a leader emerges in the United States and inspires leadership around the world to recommit to the law of peace.

Addendum

VI: Shortly after our original conversation the Trump administration ordered a drone strike in Iraq killing General Quesem Soleimani, a prominent Iranian military leader of the Revolutionary Guards Quds Force, and a number of Iraqis. Iran has declared this an extrajudicial assassination and has issued this statement by Ambassador to the United Nations Majid Takht Ravanchi in a letter to Secretary-General Antonio Guterres and the UN Security Council:

“Conducted ‘at the direction of the President’ of the United States, the assassination of [Soleimani], by any measure, is an obvious example of State terrorism and, as a criminal act, constitutes a gross violation of the fundamental principles of international law, including, in particular, those stipulated in the Charter of the United Nations and thus entails the international responsibility of the United States.” 

 Ambassador Ravanchi declared Iran has the right to self-defence under international law. What are your thoughts on the United States unilateral use of deadly force on third country territory?

Mary Ellen O’Connell: The United States has submitted a letter to the Security Council as required under UN Charter Article 51 stating that the U.S. had the legal right to kill Soleimani to prevent an “imminent” attack. Article 51, as we have discussed, permits the use of force in self-defense “if an armed attack occurs”. That means the attack must be underway and not in the mere planning phase. The actual armed attack must be significant and the response must be necessary and proportional. The right of self-defense is for a state to defend itself from another state, not to single out one military leader for execution.

Note that these principles apply equally to Iran. The killing of Soleimani was not grave enough to permit Iran to counter-attack against the U.S., let alone to attack the territory of Iraq. Iran’s attacks on military bases in Iraq on January 5 were not aimed at halting and repelling attacks for which Iraq was responsible.

If the United States had intelligence that Soleimani was plotting attacks on U.S. personnel in Iraq, the appropriate response was to take the information to Iraqi authorities. It was the duty of the Iraqis to keep the invited Americans safe from the criminal acts of others on their territory. Equally, the law required Iran to respond with measures short of military force to Soleimani’s assassination.

For more on this issue see 

https://www.ejiltalk.org/the-killing-of-soleimani-and-international-law/

Mary Ellen O'Connell is the Robert and Marion Short Professor of Law and is Research Professor of International Dispute Resolution—Kroc Institute for International Peace Studies, University of Notre Dame.

O’Connell’s research is in the areas of international law on the use of force, weapons technology, dispute resolution, and international legal theory. She is the author or editor of numerous books and articles on these subjects, including The Art of Law in the International Community (Cambridge University Press, 2019), Self-Defense against Non-State Actors (with C. Tams and D. Tladi, Cambridge University Press, 2019) and The Power and Purpose of International Law: Insights from the Theory and Practice of Enforcement (Oxford University Press, 2008, paperback 2011).