We know a lot about how to implement a ceasefire, as well as the factors that influence the likelihood that a ceasefire will be successful.  

In the case of the Russian war on Ukraine, the US has proposed a 30-day ceasefire, with the hope that it can start a process that can end the war. Ukraine has agreed to the ceasefire, but President Putin raised questions regarding how such a ceasefire will be monitored and how breaches of the ceasefire will be managed. To help answer these questions, a good place to start is by looking at lessons from the long experience of the United Nations (UN) and others with monitoring ceasefires. 

Technical Elements of a Ceasefire 

The technical elements those involved in the ceasefire negotiations would need to make decisions, including agreeing on a line of separation, a buffer zone, an exclusion zone, and a ceasefire monitoring and verification mechanism.  

Line of separation: Typically, a ceasefire has as its baseline a line of separation or ceasefire line. This is literally a line on a map that separates the two sides from each other. Crossing the line by land, sea, or air will imply a return to war. In Cyprus, for example, this is the so-called green line that separates the north from the south. In Lebanon, a blue line separated Israeli and Hezbollah forces. The line will typically be determined by the military position of both sides at the time of the agreement. The ceasefire line is agreed for the purpose of the ceasefire, and it is thus not meant to prejudice any future peace agreement. The front lines in the Russian war on Ukraine currently extend over approximately 2,000 kilometers, and mapping out every kilometer will be a substantial, but necessary, first task. 

Buffer zone: From the line of separation, there is typically a buffer zone of several kilometers that neither side may enter by land, sea, or air. This agreed demilitarized zone or no-man’s land can help avoid accidental fire or other incidents that can spark confrontations and reignite the war.  

Exclusion or limitation zone: From the line of separation, there is also typically an exclusion or limitation zone within a certain distance of the line of separation where certain types of heavy weaponry, ships, aircraft, or drones cannot be deployed or operated. This can prevent the warring forces from shelling each other and ensure that they have time to react to any hostile maneuvers from the other side.  

Ceasefire monitoring and verification mechanism: Ceasefires are entered into by countries or parties at war with each other. They don’t trust each other and thus need a means to independently verify that the other side is complying with the agreement. A ceasefire monitoring mechanism typically consists of a body that oversees the mechanism and a means to monitor compliance and investigate breaches of the agreement.  

The body that oversees the agreement—often called a joint ceasefire monitoring commission—typically consists of representatives of both sides and can be chaired by a third party, often the mediator acting as a guarantor or an organization like the UN. It reviews compliance reports and decides how to handle alleged breaches. The mechanism establishes quick and secure lines of communication between the parties, for example by deploying liaison officers. Such arrangements are critical to quickly de-escalate incidents in a context of deep mistrust between the parties.  

In most ceasefire arrangements to date, unarmed observers monitor the line of separation and the buffer zone and verify that the parties are not in breach of the exclusion zones. If there are any alleged breaches of the agreement, the third party, or a joint mechanism, investigates and reports back to the body that oversees the agreement. All these mechanisms are meant to reassure both sides that the actions of the other side are being independently monitored and verified.  

It should be stressed that none of the ceasefire operations deployed to date have been mandated to use force to prevent either side from attacking each other. There is a common misperception that UN peacekeepers in, for example, Lebanon, are supposed to use force to prevent Israel from attacking Hezbollah or vice versa. This is not the case. Ceasefire monitors are by definition unarmed, or lightly armed to protect themselves, and their role is limited to helping the parties to the agreement to monitor compliance with and facilitate the implementation of the ceasefire.  

Who Will Monitor and Verify Compliance with a Ceasefire between Russia and Ukraine? 

Who can perform the role of a neutral third party that can assist Russia and Ukraine to implement a ceasefire? It would need to be an organization or arrangement that both sides trust to be neutral and capable of professionally verifying the other side’s compliance.  

An important distinction needs to be drawn between neutral peacekeepers that monitor and verify a ceasefire agreement and other forces that may be deployed as a security guarantee for Ukraine or Russia. Both Russian and European leaders have referred at times to their own forces as peacekeepers, but this is a political rather than a technical use of the term. From the perspective of a ceasefire implementation arrangement, European forces deployed in Ukraine as a security guarantee, or Korean or other forces deployed in support of Russian forces, would have to comply with the same ceasefire arrangements as the forces they are allied to. It would not be tenable for such forces to guarantee the security of one side and be neutral, third-party peacekeepers at the same time. Security guarantees will be an important aspect of a successful ceasefire and eventual peace agreement, but such forces should not be confused with neutral ceasefire observers that may be deployed to help monitor and verify a ceasefire agreement.  

That rules out bodies like the European Union, NATO, or the Collective Security Treaty Organization (CSTO) that are associated with one side or the other. The main options left are the UN, the Organization for Security and Co-operation in Europe (OSCE), or a special arrangement established for this purpose. 

At this early stage in the negotiations, the United States (US) and Ukraine appear to favor the latter option. President Zelensky has suggested that a ceasefire between Russia and Ukraine can be monitored by US satellites and drones. It is unclear, however, if the US, which is providing arms and intelligence to Ukraine, would be trusted by Russia to act as a neutral third party to verify compliance with the agreement. There are also technical limitations to satellites and drones, such as bad weather and cloud cover. Most importantly, such an arrangement seems to lack a mechanism for investigating alleged breaches and to manage incidents in the field. Past experience, including in Donbas, indicates that there are likely to be many incidents and alleged breaches that require daily follow-up. If US remote monitoring of the ceasefire is not sufficient on its own, an alternative is to consider monitoring by the UN or the OSCE. 

Russia, Ukraine, and most other states supporting one of the warring parties are members of the OSCE. The OSCE has experience with ceasefire monitoring, including in Ukraine, where it monitored the Minsk ceasefire agreement in the Donbas between 2014 and 2022. A challenge with the OSCE, however, is that its decisions are consensus-based and nonbinding. A further challenge is that many, if not all, of the members of the OSCE have come out in support of one or another of the parties to the conflict. An OSCE ceasefire mission would thus probably have to ensure its neutrality by establishing monitoring teams that consist of citizens of countries that have been aligned with both sides so that they can monitor each other. Deploying and managing such a mission would be a significant challenge. 

The final option—the UN—would come with several advantages. The UN is the international organization with the most experience in deploying and managing ceasefire observer missions. It could draw observers from a global pool of troop-contributing countries that may be acceptable to both sides. It has a well-oiled mechanism for deploying, overseeing, and funding such a mission. Most importantly, UN missions are deployed and overseen by the UN Security Council where Russia, the US, China, France, and the United Kingdom are permanent members with veto powers. Although Ukraine is not a member, the presence of key allies like France and the United Kingdom and the role of the US as mediator and guarantor would probably give them sufficient confidence that their interests would be protected in the UN Security Council. The UN Security Council would be asked to endorse a ceasefire agreement, so if the parties want the help of the UN to independently verify compliance, it would be naturally suited to this role.  

The most likely mechanism would be some combination of these options. Monitoring a line of separation, as well as buffer and exclusion zones, 24/7 over approximately 2,000 kilometers will be a huge challenge. It will require not only the use of technology such as satellites and drones but also boots on the ground to deal with incidents, manage exceptions such as allowing civilians access to the buffer zone for specific purposes, and investigate alleged violations. This could be managed by a joint mechanism that includes both sides and perhaps the guarantor. Russia and Ukraine have the advantage of already having a presence on the ground, knowing the terrain, and being able to communicate.  

Past experiences with such joint mechanisms show, however, that the parties often use such mechanisms as a micro battle space where they withhold or manipulate information and continuously spar over every issue. Deploying civilian or unarmed military observers by a neutral third party like the UN could help to overcome these trust issues and facilitate the working of such a joint mechanism. This would take time, and sending more than a few dozen UN experts to support the first phase of the process may thus not be an option in the short term. However, if the ceasefire becomes more permanent, and if Russia and Ukraine find it challenging to monitor the ceasefire on the ground on their own, deploying a UN ceasefire observer mission to facilitate the process could be an option worth considering. 

Factors That Influence the Success of Ceasefire Arrangements 

With 80 years of experience from the UN and an even longer history of other experiences to draw on, policymakers and academics have a solid understanding of the factors that influence the likely success of ceasefire agreements. Two factors stand out: legitimacy and credibility.  

First, the degree to which the agreement and arrangements are perceived as legitimate and viable are critical to their success. Do the parties to the agreement and other key stakeholders have a shared understanding of what they want to achieve and how they will go about it? In other words, is there sufficient political commitment and public support to make the ceasefire viable? 

Second, for the ceasefire mechanism or operation to be complied with and trusted, it needs to be perceived as being capable to credibly carry out the monitoring and verify tasks entrusted to it. Does the arrangement have the leadership, staff, equipment, and resources necessary to monitor and verify compliance, investigate breaches, and act assertively to maintain confidence when critical incidents raise emotions and undermine trust? In other words, do the parties to the agreement and other key stakeholders have sufficient confidence that the arrangements will hold up under stress? 

Regardless of what kind of mechanism is agreed on to oversee a ceasefire agreement between Russia and Ukraine, it will face a momentous task. Both sides and the mediator will have to develop a shared understanding of the critical elements that need to be in place to ensure success, as well as a degree of pragmatism and flexibility to resolve problems as they arise. The most important ingredient will be sustaining the political will to make it work. 

Cedric de Coning is a research professor with the Norwegian Institute of International Affairs (NUPI) and a senior advisor to the African Center for the Constructive Resolution of Disputes (ACCORD).