Ukraine Symposium – Negotiating an End to the Fighting

As the conflict in Ukraine grinds on with no end in sight, speculation over the possibility of negotiating an end to the fighting continues. Most discussion has centered on the terms of any such agreement. Issues on the table have included, inter alia, the withdrawal of Russian troops, external guarantors, the status of the so-called Donetsk and Luhansk People’s Republics, and Russian sovereignty over Crimea.

Unfortunately, the track record of agreement between Russia and Ukraine is far from encouraging. Recall that the two countries agreed to “respect each other’s territorial integrity, and confirm the inviolability of the borders between them” in the 1997 Treaty on Friendship, Cooperation and Partnership. Yet, in 2014, Russia occupied Crimea, which promptly issued a Declaration of Independence and was soon annexed by Russia. That same year, armed separatist groups in Luhansk and Donetsk (the Donbas region), supported by Russia militarily, declared independence.

The cease-fire that followed soon thereafter (Minsk I) proved short-lived. It was followed by Minsk II in 2015, which provided for a cease-fire, withdrawal of heavy weapons from a security zone, OSCE monitoring and verification, and dialogue about autonomy for Luhansk and Donetsk. Despite the agreement, sporadic hostilities broke out, leading to a “frozen conflict” like those in other post-Soviet States (Moldova, Georgia, and Azerbaijan/Armenia). The Russian “special military operation” launched in February of this year sounded the death knell for Minsk II.

Intermittent negotiations between the belligerents have been underway since then but are now stalled. Although President Zelensky indicated on Saturday that an end to the conflict would require a diplomatic solution, his Chief of Staff quickly clarified that a cease-fire was off the table for the time being, at least if it involved any territorial concessions.

An international armed conflict can end through unconditional surrender, as was the case with Germany and Japan during World War II. Debellatio, which denotes the complete occupation of a defeated country that no longer has a meaningful armed force or government, also signals the end of such a conflict. And as a general matter, the applicability of most international humanitarian law ceases upon the “general close of military operations,” which is usually understood as the “final end of all fighting between all those concerned” (GC IV, commentary to art. 6; see also 1987 Additional Protocol I, commentary to art. 3; UK Manual of the Law of Armed Conflict, ¶ 3.10).

This post examines three negotiated modalities for ending the fighting – cease-fires, armistice agreements, and peace treaties. As will be explained, the first merely suspends the fighting, while the other two end the armed conflict altogether. Moreover, their requirements and limitations differ, making them suitable for differing circumstances. But the discussion must begin with the confusing terminology used to describe agreements to end hostilities.

Terminology

The U.S. Department of Defense Law of War Manual distinguishes between an armistice and a peace treaty, suggesting that the former only suspends operations, whereas the latter ends the armed conflict (§ 12.11.1.1). As to armistices, the Manual observes that the term also “has been referred to as a truce, local truce, cease-fire, cessation of hostilities, and suspension of arms” (§ 12.11.1.2, see also Leslie Green, Contemporary Law of Armed Conflict, 3rd ed., pages 104-108; Sassòli et al., How Does Law Protect, here, here, and here).

Yet, the Law of War Manual’s binary terminological division is not universally accepted. For example, “armistice” is sometimes used to refer to an agreement that suspends hostilities with an eye toward a permanent end to the armed conflict, while “cease-fire” occasionally refers only to agreements to suspend hostilities for other purposes.

Confusing matters is the fact that the Manual’s approach does not reflect the way the terms have been used in practice over the last century. As Yoram Dinstein has explained in his classic work War, Aggression and Self-Defence (6th ed., pages 36-64), in contemporary usage “cease-fires” suspend hostilities, “armistices” terminate the armed conflict, and “peace treaties” restore peaceful relations between the belligerents (see also Max Planck Encyclopedia entries by Dinstein and Bell; Handbook of Humanitarian Law, Kleffner, 4th ed., § 3.31-3.32; NY Times).

In my estimation, Dinstein’s typology best replicates current State practice and is of greater practical use. Therefore, I adopt it in this post. However, my purpose here is not to resolve the unfortunate terminological dissonance. Instead, I write to highlight the three fundamental avenues of approach for negotiating an end to the fighting – suspending hostilities, ending the conflict, and restoring peace.

Suspension of Hostilities: Cease-fires

Factually, parties to a conflict may simply stop fighting for reasons ranging from operational pauses or stalemates to inclement weather that temporarily makes combat impossible. But hostilities can also be suspended by legal means. Traditionally, the term “truce” or “armistice” denoted an agreement between the parties to stop fighting temporarily. Yet, as will be explained in the next section, the latter term has come to refer to one form of agreement that terminates an international armed conflict altogether. Today, the expression “cease-fire” is colloquially used to indicate a suspension of hostilities through agreement; it encompasses the older term “truce.”

Cease-fires are provided for (albeit using the term “armistice”) in Articles 36-41 of the Regulations annexed to the 1899 Hague Convention II and the 1907 Hague Convention IV, which reflect customary law and are therefore binding on all States (Nuremberg IMT Judgment, Nuclear Weapons Advisory Opinion, para. 80; Meron). The numbering and substance of the articles are identical in the two instruments, with only a few words distinguishing them.

Such agreements come into effect either at the date and time agreed upon or, if none, once the forces of both sides have been notified (Art. 38). The Hague Regulations provide that a cease-fire agreement may be for a set period or an indefinite duration. In the latter case, either party may resume hostilities whenever it chooses, so long as the other party is warned according to the notice period provided in the agreement (Art. 36). Should one of the parties seriously violate the cease-fire, its opponent may denounce the agreement and, if necessary in the circumstances, immediately resume hostilities (Art. 40). Additionally, the agreement should establish how communications between the parties are to take place (Art. 39).

It must be cautioned that only a serious material breach justifies the resumption of hostilities. Moreover, should “private persons acting on their own initiative” violate the terms of the cease-fire, the “injured party” may only demand punishment or compensation for losses it may have sustained as a result of that breach. It may not resume hostilities against its adversary on that basis unless the conduct of the “private persons” is attributable to the adversary (Art. 41).

Cease-fires may be “general” or “local” (Art. 37). Local cease-fires are restricted to a limited area and used for purposes such as making possible negotiations between the parties, recovering bodies, or facilitating humanitarian relief. At times, the parties to the Ukraine-Russia conflict have negotiated temporary local cease-fires, most notably during the siege of Mariupol (e.g., see here). And last week, Italy presented a plan to the UN Secretary-General calling for local cease-fires to enable civilian evacuations, as well as a broader agreement leading to peace.

Some local cease-fire purposes are provided for in law. Of particular note in the Ukraine-Russia conflict is Article 15 of the 1949 Geneva Convention I. Using the traditional term “armistice” but referring to a suspension of hostilities, and therefore a cease-fire as the term is used in this post, provides in relevant part,

Whenever circumstances permit, an armistice or a suspension of fire shall be arranged, or local arrangements made, to permit the removal, exchange and transport of the wounded left on the battlefield.

Likewise, local arrangements may be concluded between Parties to the conflict for the removal or exchange of wounded and sick from a besieged or encircled area, and for the passage of medical and religious personnel and equipment on their way to that area.

General cease-fires suspend hostilities between the parties everywhere. Their purposes range from allowing for negotiations to merely recognizing a mutual desire to end the fighting without formal acquiescence to any consequence of the conflict, such as territorial gain.

General cease-fires are typically written but need not be. They usually set out the agreed disposition of forces at the time they come into effect. A cease-fire may also indicate which operations are permissible and which are not during the cease-fire period. For instance, the 1991 cease-fire agreement between Coalition forces commanders and their Iraqi counterparts that preceded Security Council Resolution 687 (containing formal cease-fire terms) allowed Iraq to use helicopters, but not fixed-wing aircraft. That judgment error made possible their use against the Kurds and Marsh Arabs and motivated the establishment of no-fly zones in northern and southern Iraq. Similarly, the 1999 Military Technical Agreement between the International Security Force (‘KFOR’) and the Governments of the Federal Republic of Yugoslavia and the Republic of Serbia (‘MTA’) set forth terms, such as the establishment of air and ground safety zones, that made ending the fighting between NATO and the FRY viable.

As the DoD Law of War Manual notes (§ 12.11.4.5), in the absence of such prohibitions, a belligerent is allowed to:

to make movements of forces within its own lines;

to receive reinforcements;

to construct new fortifications, installations, and bases;

to build and repair transportation and communications facilities;

to seek information about the enemy;

to bring up supplies and equipment; and

in general, to take advantage of the time and means at its disposal to prepare for resuming hostilities.

There have been numerous calls for general cease-fires in this conflict. For instance, Secretary of Defense Lloyd Austin urged Russia’s Defense Minister, General Sergei Shoigu to accept one during their May 13 phone call. Unfortunately, it fell on deaf ears. And in addition to the local cease-fires cited above, Italy has offered a plan leading to peace that would begin with a general cease-fire and demilitarization of the frontlines.

It must be emphasized that as a matter of law, the armed conflict continues during a cease-fire; the fighting is merely suspended until the cease-fire ends by its own terms or a Party breaches a material term and the opponent elects to resume hostilities. However, a cease-fire can, but need not, precede a permanent end to the hostilities by means of an armistice or even a peace treaty.

End of the Armed Conflict: Armistice

As noted, the term “armistice” historically denoted a suspension of hostilities. Since the Second World War, however, it refers to an agreement that ends the armed conflict without fully restoring peace between the belligerents. Yoram Dinstein has noted that the trend began with the Armistice of 11 November 1918, which ended the First World War. However, the restoration of peaceful relations with Germany was only achieved with the 1919 Treaty of Versailles. This trend continued during and after the Second World War, as illustrated by Italy’s declaration of war on Germany in October 1943, a month after it concluded an armistice with the Allies. The declaration of war was only possible because the armistice had ended the armed conflict with Allied forces. In 1947, Italy and the Allies concluded the Paris Treaty of Peace.

Unlike a cease-fire, an armistice agreement may not be concluded solely at the discretion of operational commanders. It is a formal instrument qualifying as a treaty and, therefore, must be executed on behalf of the governments concerned. And because it ends the armed conflict permanently, it may not be local or of limited duration, cannot be denounced, and material breach does not allow the aggrieved party to resume hostilities. Accordingly, under an armistice agreement, the parties lose the right to resume hostilities altogether.

Should hostilities subsequently break out between the Parties to an armistice, a new armed conflict will be triggered. Moreover, since hostilities have ended permanently, any resumption would qualify as an unlawful “use of force” under Article 2(4) of the UN Charter and customary law unless authorized by the U.N. Security Council under Chapter VII of the UN Charter or engaged in pursuant to the customary right of self-defense reflected in UN Charter Article 51. To illustrate, the 1953 Korean War Armistice ended the war between North and South Korea (and China and the UN Command) as a matter of law, but restoration of peace between the two countries awaits a peace treaty. If North Korea attacks, it will violate the UN Charter prohibition on the use of force and trigger a new international armed conflict.

Several steps contained in the previously-mentioned Italian peace plan proposal could be included in an armistice agreement between Ukraine and Russia (or even a broader peace treaty). They include a conference leading to Ukraine’s acceptance of neutrality, an external security guarantee, a bilateral agreement between Russia and Ukraine to clarify the situation in the Donbas and Crimea, and a multilateral agreement between the European Union and Russia that provides for the staged withdrawal of Russia troops and the lifting of sanctions on Russia.

But an armistice does not necessarily settle matters between the former belligerents once and for all; that usually is accomplished through the mechanism of a peace treaty. For instance, the aggressor in the conflict may have seized territory in violation of international law, as in the case of Russia’s unlawful seizure of Crimea, parts of southern Ukraine, and most of the Donbas region. An armistice would not necessarily signal an acknowledgment of Russian (or its proxy People’s Republics’) claims to the territory, nor could it, for a treaty may not sanction territorial acquisition by conquest (see below). However, such an agreement would likely contain lines of demarcation separating forces or territory under the control of the respective Parties that serve as de facto borders.

Restoration of Peace: Peace Treaty

As Jann Kleffner has observed, “much as declarations of war have become the exception and contemporary international armed conflicts between States regularly begin without such formal pronouncements of the actual outbreak of hostilities between States, wars and international armed conflicts are often terminated by less formalized modes than by peace treaties.” Nevertheless, there is no question that they remain formal instruments of international law serving particularly useful purposes. Indeed, Italian Prime Minister Mario Draghi discussed the possibility of a Ukraine-Russia peace treaty with President Biden during his mid-May visit to the United States.

Peace treaties need not be preceded by an armistice, although in many cases, they are, as with the World Wars (see above). And sometimes, peace treaties come long after the armed conflict is over. For example, the Second World War peace treaty between Germany and the Allied nations was executed only in 1990.

A peace treaty always terminates the armed conflict if not already accomplished through armistice or conduct (see below). However, unlike an armistice, a peace treaty also reestablishes peaceful relations between the parties. They, therefore, may contain an array of terms, ranging from the means by which borders are to be settled to the payment of reparations.

However, the sine qua non characteristic of a peace treaty is that it legally reestablishes regular state-to-state relations between the Parties, which Dinstein labels “normalization.” For instance, the Italian peace plan submitted to the U.N. Secretary-General contains some proposed provisions that could appear, as discussed above, in either an armistice or a peace treaty. Others, like autonomy for Crimea and Donbas, cultural and language rights provisions, and a “guarantee [of] the free movement of people, goods and capital,” would be more likely to appear in a peace treaty.

Normalization does not necessarily mean relations are warm. But over time, that is often the result. Recall that alongside some of its former adversaries, the Federal Republic of Germany joined NATO in 1955 and has been a European Union member since 1958. Yet, it was only with the reunification of Germany that a peace treaty became possible.

Like an armistice, a peace treaty is an international agreement. As such, it is subject to rules outlined in the 1968 Vienna Convention on the Law of Treaties for Parties to that instrument and to the customary law reflected in it for non-Parties like the United States. The most significant provision bearing on peace treaties is Article 52. It provides that “[a] treaty is void if its conclusion has been procured by the threat or use of force in violation of the principles of international law embodied in the Charter of the United Nations.” As explained in Mark Villiger’s Commentary on the 1969 Vienna Convention, the term “procured … requires a direct causal relationship between coercion and the conclusion of the treaty, i.e., the treaty would not have been concluded if there had not been a threat or use of force” (page 645). This means, for example, that while victors may impose treaties of peace on their adversary, States that have violated the prohibition on the use of force may not do so. For example, if Russia prevailed in this conflict, it could not compel Ukraine to execute a peace treaty.

It is important to note that Article 52 provides that such a treaty is “void,” which means that the instrument’s provisions have no “legal force” [art. 69(1)]. The Villiger Commentary observes that even “subsequent approval of a treaty procured by coercion does not appear possible” (page 647). Thus, for instance, a peace treaty imposed on Ukraine by Russia that purported to cede territory to Russia or require recognition of the so-called People’s Republics would be of no legal effect. Further, Article 44(5) confirms that treaties secured by an aggressor are not severable. Accordingly, no provision of such a treaty between Russia and Ukraine would be valid, even one favoring Ukraine. Only a peace treaty that involved no duress by Russia would bind the parties.

As it stands now, the prospect of territorial sacrifice to secure a peace treaty is off the table. On 22 May, for instance, Ukraine’s lead negotiator in talks with Russia confirmed, “Any concession to Russia is not a path to peace, but a war postponed for several years. Ukraine trades neither its sovereignty nor territories and Ukrainians living on them.”

In that regard, it is clear that the acquisition of territory through the unlawful use of force cannot result in the transfer of sovereignty. This is a longstanding rule of law recognized in the U.S. Military Tribunal’s 1949 Greifelt (RuSHA) judgment (page 154).

Any purported annexation of territories of a foreign nation, occurring during the time of war and while opposing armies were still in the field, we hold to be invalid and ineffective. Such territory never became a part of the Reich but merely remained under German military control by virtue of belligerent occupancy.

Article 4 of Additional Protocol I to the 1949 Geneva Conventions, to which Russia and Ukraine are Party, makes the same point: “Neither the occupation of a territory nor the application of the Conventions and this Protocol shall affect the legal status of the territory in question.” The ICRC’s 1987 Commentary (¶ 172) to the article explains,

Everyone recognized this principle as an uncontested principle of international law which was, moreover, underlying both the Hague Regulations and the fourth Convention. Nowadays it follows from the inadmissibility of the use of force, as laid down in the Charter of the United Nations, and elaborated in the Declaration on Principles of International Law concerning friendly Relations and Cooperation among States in accordance with the Charter of the United Nations (Resolution 2625 (XXV) of the United Nations General Assembly). The only question that was disputed by a minority was whether it was appropriate and necessary to repeat this principle in the present article.

Unnegotiated End to the Conflict

As a matter of law, and as noted, it is not necessary to negotiate a formal agreement to terminate an international armed conflict. Rather, an international armed conflict ends “with a general close of military operations, with no real likelihood of a resumption in hostilities” (Milanovic, page 174; see also DoD Law of War Manual, § 3.8.1.2). This could occur, as noted, through unconditional surrender or debellatio.

Indeed, hostilities may simply come to an end de facto. However, standing alone, an extended pause in the hostilities does not suffice to terminate the armed conflict. The absence of hostilities only does so when accompanied by evidence of the intention of the parties to end the conflict conclusively, as in the case of re-establishing diplomatic relations or a declaration by one (if met with no objection) or both of the parties that the armed conflict is over. As Marco Sassòli has explained, “[w]ithout declarations or agreements, a relatively long time must pass before it can be determined whether an absence of hostile military operations corresponds to a close or just to a lull” (pages 191-92).

The same logic applies to the reestablishment of peaceful relations. For instance, the resumption of robust trade, cultural exchanges, the provision of foreign aid, or the adoption of a mutual defense agreement could signal the return of peaceful relations.

Conclusion

As noted, there have been repeated calls for cease-fires throughout the conflict in Ukraine, usually for humanitarian reasons (see here, here, and here). Sadly, only a few have been heeded. Hopefully, more will be negotiated, and in that regard, it is crucial to understand that there are many purposes for suspending the fighting, including the negotiation of a more permanent end to the conflict. But it will continue to be an uphill battle to negotiate even a temporary halt to the fighting.  As a senior adviser to President Zelensky has warned,

The war will not stop (after any concessions). It will just be put on pause for some time. After a while, with renewed intensity, the Russians will build up their weapons, manpower and work on their mistakes, modernise a little, fire many generals … And they’ll start a new offensive, even more bloody and large-scale.

When the international armed conflict, as distinct from the fighting, finally ends, it is likely to occur through an armistice agreement (as that term is used in this post). The question is how long will President Putin be willing to continue to pursue his aggressive war against Ukraine despite its failure to achieve its original objectives and the costs being imposed on it and the Russian people.

And there is a legal fly in the ointment. It is clear from Common Article 2 of the 1949 Geneva Conventions and customary international law that an international armed conflict continues during the belligerent occupation of a party’s territory. Therefore, if an armistice agreement between Ukraine and Russia is to end the armed conflict, it would either have to provide for the withdrawal of Russian troops or to include implicit or explicit Ukrainian consent to their continuing presence, thereby changing the situation from one of occupation to consensual basing. Should the agreement not adopt either course of action, it would effectively amount to a general cease-fire because the international armed conflict would continue, as a matter of law, despite the indefinite suspension of hostilities. In my view, this is the likeliest scenario (see also here)

Finally, a peace treaty in the foreseeable future is unthinkable. Given the horrific abuses that Russian forces have committed, it is difficult to imagine Ukraine agreeing to the normalization of relations any time soon. And voluntary territorial concessions by Ukraine appear out of the question. So for the time being, a general cease-fire is the best negotiated solution for which we can hope.

***

Michael N. Schmitt is the G. Norman Lieber Distinguished Scholar at the United States Military Academy at West Point. He is also Professor of Public International Law at the University of Reading and Professor Emeritus and Charles H. Stockton Distinguished Scholar-in-Residence at the United States Naval War College.

Photo credit: Oleksandr Ratushniak / UNDP Ukraine