How Can Ukraine's Security Be Guaranteed?

Is there a role for a European multinational force?

As the Trump administration embarks on its quest to bring peace to Ukraine, discussed in my previous post, one of the big issues waiting to be addressed is how Ukraine’s future security will be supported as part of any deal.

Consideration of this issue has led to proposals for a multi-national force, which would be largely European. This has sometimes been described as a ‘peacekeeping force’, including by Keir Starmer when speaking about a possible UK contribution, but elsewhere it has been described as a ‘deterrent’ or ‘trip-wire’, though these are very different concepts.

So far there has only been preliminary discussions about these ideas so a certain amount of loose language can be expected. But these labels matter because they can mislead as to the scale of the effort involved or imply more than can reasonably be delivered. Can security really be ‘guaranteed’? Is there a peace to be ‘kept’? Security guarantees can come in a variety of forms, as Bruno Tertrais demonstrated in his post of July 2023. Some will be taken more seriously than others.

My aim in this post is to help to bring some clarity to the discussion by unpacking these concepts and relating them to the current situation in Ukraine. All current proposals raise conceptual and practical problems, especially once they are closely linked to a ceasefire. Europeans do need to give thought as to how they can support Ukraine more in the future, but in the context of continuing hostilities as much as their cessation.

Security Guarantees

Security guarantees are a means of reassuring vulnerable states that they others will come to their rescue if attacked by neighbouring predators. By offering these guarantees the predators hopefully will be deterred. The gold standard remains Article V of the 1949 North Atlantic Treaty, in which ‘The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all.’ Should such an attack occur each Party agrees to assist those attacked

‘by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.’

This has only been invoked once – after the al Qaeda attack on the United States of 11 September 2001. This was an important act of solidarity but it made little difference to any military calculations at the time. The enemy here was insidious but not exactly another great power with a full set of military capabilities.

Although the commitment sounds firm, and a member has never invoked it only to be refused, it does not involve automaticity. The get-out clause is that an ally will act as it ‘deems necessary,’ and of course it may deem it necessary to do nothing at all. There is no reason in principle why a treaty cannot specify exactly what would be expected of the parties in the event of war but the major powers do not like to be boxed in by tight commitments. There is always some wiggle room.

This is not surprising. It is one thing to rush to support a country that has been the victim of naked aggression but quite another to back one that has been acting irresponsibly or is in so much difficulty that no rescue Is possible. Even when full support is warranted and there are feasible militarily options, action may seem too risky and lack public backing. Nonetheless, when a security guarantee has been issued there will still a cost when it is not honoured, for that will diminish the credibility of all other comparable commitments. It risks being seen as a great betrayal, with the obligatory references to Munich and Czechoslovakia in 1938. Russia’s attempt to mimic NATO with its own Collective Security Treaty Organisation (CSTO) has faltered because its members regularly feel let down by Russia. Other than Belarus, to a limited extent, none have acted in support of Russia in Ukraine.

There always two audiences for a guarantee; the state(s) being assured and the state(s) being deterred. The vital test is deterrence, for that is the essential purpose of a security guarantee. A potential aggressor knows that if it launches an attack its victim will be immediately supported by other, possibly larger, states. As the exact circumstances in which the test might arise cannot be known in advance, there is bound to be uncertainty about whether it will be passed. But the potential adversary dare not dismiss deterrent threats completely. Even when the likelihood of the guarantor acting as threatened may seem low the consequences should it do so may be very high, and so the risk may not be worth taking. So far Russia has taken care not to pose an Article V test to NATO. A less severe threat, for example reprimands and economic sanctions, is more likely to be implemented but less likely to act as a restraint, and that too has been the case with Russia.

For the country being backed by a guarantee there will be unavoidable uncertainty surrounding its value. Over time it may appear to be working, but, as with all deterrents, appearances can be deceptive. The absence of acts of aggression is not necessarily evidence of an effective deterrent. There may be all sorts of reasons why the potential aggressor has not acted, from a lack of intention to just waiting for an opportune moment to pounce. Thus the test may come, if at all, many years after the guarantee has been issued. Will a promise made by one government be honoured by another in a very different set of circumstances? As with all guarantees, a reluctant guarantor can always find an exclusion clause in the small print.

This is why the first test is not deterrence but assurance. In the light of the inherent uncertainties surrounding any guarantee can it be relied upon? In practice vulnerable states may have little choice but to be reassured. The guarantee may be borderline incredible and so the reassurance delusional but it may still be better than nothing. As the history of NATO demonstrates, allies will live with uncertainty, while pressing all the time for more assurances, and more conspicuous demonstrations of support.

Budapest Memorandum

Ukraine has more reason to be sceptical of security guarantee than most because it was let down in the past. In 1994 it gave up the nuclear arsenal inherited from the old Soviet Union (which at the time was pretty useless as it was not controlled from Ukraine and they lacked the resources to turn them into a sustainable force). In the Budapest Memorandum, in addition to a good financial package, Ukraine was compensated with an undertaking from the US, UK, and Russia, and then later France and China ‘to respect the independence and sovereignty and the existing borders of Ukraine’, which meant not threatening force or engaging in economic coercion, and to provide assistance ‘if Ukraine should become a victim of an act of aggression or an object of a threat of aggression in which nuclear weapons are used.’

Pretty clear one might think. Yet when twenty years later Crimea was annexed by Russia, one of the parties, the others did little other than complain and impose limited economic sanctions. When Vladimir Putin was asked about the violation of Ukrainian sovereignty his slippery explanation was that because of the changed government in Kyiv: ‘a new state arises, but with this state and in respect to this state, we have not signed any obligatory documents.’ Later on, Foreign Minister Lavrov tried a different argument, erroneously claiming that it contained ‘only one obligation—i.e., not to use nuclear weapons against Ukraine. No one has made any threats to use nuclear weapons against Ukraine.’ As for the lack of a robust response from the US and UK this fitted with the language of the memorandum which referred to assurances rather than guarantees. This might appear to be a distinction without a difference, but assurances do not imply military force, and there was a question whether any stronger language then could have been ratified by the US Senate.

Ukraine and NATO

This helps explain why Ukraine wants a more reliable commitment this time round. As far as President Zelensky is concerned this can only truly be achieved through Ukraine becoming a member of NATO. This is not just because of Article V. It would become part of a large collective security organisation, which has an integrated military command, with states sharing standards and working together on equipment projects, force planning, arms purchases and exercises.

Ukraine’s wish to join NATO has been around since the early 2000s but after the alliance’s Bucharest summit of 2008 the issue was on the back burner. In a messy compromise between Chancellor Merkel of Germany and US President Bush, the possibility was kept open but nothing was done to advance Ukraine’s membership. While leaving Kyiv disappointed, the mere possibility of future Ukrainian membership of NATO provided Putin with a rationale for the full-scale invasion of February 2022. One of the many specious arguments he used was that as a member of NATO Ukraine could embark on a campaign to retake Crimea and defeat the pro-Russian enclaves in Donetsk and Luhansk by invoking Article V and getting active support from the rest of the alliance. Article V of course does not work that way. The principle is that an attack on one should be viewed as an attack on all, not that an attack by one should turn into an attack by all.

Ukraine made a formal application to join the alliance on 30 September 2022. This got a sympathetic reception, but when then issue was addressed in the summer of 2023, Zelensky was left disappointed again. President Biden observed, ‘I don’t think there is unanimity in NATO about whether or not to bring Ukraine into the NATO family now, at this moment, in the middle of a war.’ The agreed formula was that NATO ‘will be in a position to extend an invitation to Ukraine to join the Alliance when Allies agree and conditions are met’ and that ‘the security of Ukraine is of great importance to Allies and the Alliance.’

Zelensky has continued to push for NATO membership, even more so in the context of the push for a peace deal. Once the firing stopped Ukraine could have little confidence that Russia, with its business unfinished, would not invade again. In this he has been given regular support by NATO Secretary General Mark Rutte. Rutte repeated this support at Davos, arguing that

‘Our focus has to be putting Ukraine in the best possible position and peace talks will start. And when they end, we have to make sure that the peace we have collectively fostered is sustainable, will never ever be challenged again.’

He was slapped down by one of Trump’s aides Richard Grenell,

‘You’re going to run into a big buzz saw on America if we have the Nato secretary general talking about having Ukraine to Nato. The American people are the ones that are paying for the defence. You cannot ask the American people to expand the umbrella of Nato when the current members aren’t paying their fair share.’

In this way the issue is caught up with Trump’s well known conviction that the allies are not paying enough. This is going to colour all transatlantic relationships, at least until the Europeans significantly raise their defence spending. Given that Trump also believes both that Ukraine’s potential membership of NATO was a trigger for Russia’s invasion and that to propose it now would ruin any chance of a deal, NATO membership is not an option for now.

Peacekeepers and Tripwires

A ceasefire or peace treaty could well include some words guaranteeing Ukraine’s security (and probably Russia’s as well). But they will not be taken seriously in Kyiv, given the contempt shown by Moscow for those offered in the past. Already there are many statements from NATO and individual members asserting the importance of Ukraine’s security and why it is a vital interest.

To give these statements some substance, consideration is now being given to basing European troops in Ukraine, but to what purpose remains unclear. The language implies three distinct missions:

Peacekeeping

Historically peacekeeping forces, wearing blue-helmets and lightly armed only for self-defence, have been introduced to reinforce cease-fires. They are normally deployed along the line of contact under the auspices of the United Nations. Their task is to ensure the separation of the belligerents’ armies and to monitor any infractions of the ceasefire. Such a force does not seem appropriate in this case. The line of contact at some 1,300 km would require a huge number of troops to police it and they would be thinly spread.

As we saw with the full-scale invasion, knowing what the Russians were up to was not the problem. Their build-up of forces was watched carefully and their movements into Ukraine soon recorded. If improved intelligence on possible troop movements was needed further technical means could be introduced.

There was also then a border monitoring mission, set up by the Organisation of Security and Cooperation in Europe (OSCE) in place when the Russians invaded. This was described as the ‘impartial monitor of the international community on the ground’, supposedly checking observance of a ceasefire along the then smaller line of contact between the Russian-backed enclaves in Donetsk and Luhansk and the rest of Ukraine. It had no effect.

If a peacekeeping force was to be sent to Ukraine under UN auspices then this would normally require Security Council authorisation which would be subject to a Russian veto. That would not be a recipe for anything of much value. An alternative UN route is to convene the General Assembly under the "Uniting for Peace" resolution which could recommend collective measures, including peacekeeping forces, but this would not be binding. Peacekeeping forces also often come from non-aligned countries, which would not reassure Ukraine.

Tripwire

A more robust alternative would be a ‘tripwire’ force, sometimes also called a ‘plate glass.’ The term came into use during the Cold War when allied troops were based close to the front line at the inner-German border. They might not be sufficient to block an advancing Warsaw Pact force but so long as they engaged the enemy the war would be widened and the allies would be fully engage in the fight. It created a credible risk of escalation. On this basis the important thing was not the size of the force but the fact of its existence. The minimum requirement for a tripwire was once described as a single American soldier who must be killed.

The advantage of a tripwire therefore is that the force does not have to be too large and would be affordable. As a small force would lack an offensive capability it should not be considered provocative by Russia. But it would only work if there was a link between the troops on the ground and the larger capabilities that could be brought to bear once the wire was tripped.

Away from the special circumstances of Cold War Europe would a tripwire work? A 2021 analysis by Dan Reiter and Paul Poast suggests not, noting that the ‘deaths of troops in combat will not necessarily create a strong public motive to intervene in order to seek revenge or protect a country’s reputation’, and that even if intervention was prompted, ‘potential attackers could strike anyway in order to achieve a fait accompli and create a strong defensive position.’

Deterrent Force

They argue that it is best to deter through a substantial contingent of troops that can influence the local balance of power. This will make the risks of launching an attack more tangible to an aggressor. NATO was never comfortable with the trip-wire and from the 1960s there were efforts to boost front-line conventional forces to convince Moscow that an invasion might not make much progress.

Up to the 2022 invasion, for example, the strategy for defending NATO’s eastern flank was a form of trip-wire, but this is now considered insufficient to reassure the Baltic states and Poland. To deter future Russian aggression allied forces deployed to the region have been boosted. An alliance official was quoted in 2023 as describing the tripwire strategy as ‘threadbare’. In the event of a Russian invasion, ‘the first battle must be the most important one.’ The challenge is at the very least to hold the front line sufficiently to allow for reinforcements to surge in from outside. A deterrent force therefore would be the most credible option, but also the most demanding in terms of the size and quality of the deployed force.

A Role for European Forces?

Zelensky is looking for a way to convince Putin that if Russia aggresses again this time Western forces will be directly engaged from the start. While at Davos he spoke of the need for 200,000 European peacekeepers to prevent another Russian attack. ‘It's a minimum. It's a minimum, otherwise it's nothing.’ This would be a substantial force, more than the UK’s current armed forces, and larger than the invasion force assembled by Russia in 2022. It is much larger than the sort of force currently under discussion.

Discussions on this matter in Europe are only at a preliminary stage. President Macron raised the possibility of European deployments a year ago, but this was in the context of boosting Ukrainian defences at a time when there was a hiatus in American support. He was talking about a training mission based safely in western Ukraine and he did not then get much support from his partners. Macron has raised it again in the context of the American peace initiative and has been canvassing support.

Details are currently sketchy. Reporting suggests that four or five European countries would be expected to contribute. A deployed force would be around 40,000 to 50,000 troops. A good rule of thumb is to deploy one unit, three are needed in total because of the need to prepare forces prior to deployment and then to recover those that have been deployed. So if say 45,000 are committed in total then the deployed force may be no more than 15,000. To get 40,000 deployed would require well over 100,000 assigned to the mission. This therefore will require much more than token forces.

In addition to the French and UK, the German defence minister has been positive (although he may be out of office soon), the Italians cautious, while the Poles sceptical. Polish Prime Minister Donald Tusk didn’t rule it out, but told journalists he wanted to ‘cut short any speculation’ on the idea. Lithuanian Foreign Minister Kęstutis Budrys was more supportive. Turkey is a member of NATO but closer than others to Russia so a Turkish contingent might be seen in Moscow as less provocative.

Any deterrent effect would depend on how well they could fit in with Ukraine’s own forces, which would also need to be boosted, how much advanced air power they could bring with them, and the extent to which there would be some tripwire effect, in that once some outside forces were fighting, more could be expected to follow.

Even if sufficient European countries could be persuaded to contribute to a sizeable force with real deterrence potential, there are still two big obstacles to making it work.

First, the American role. The only safe assumption is that Trump will not only rule out the deployment of US troops into a potential war zone but also has no intention of sending any additional US forces to Europe. Nonetheless the US will still need to be involved if a substantial force is to be deployed into Ukraine.

Here we come to the awkward precedent of the Libyan intervention of 2011, when a mission to protect rebels against the Gaddafi regime who were about to be slaughtered in Benghazi, was led by France and the UK. (This eventually led to Gaddafi being killed by rebel forces). The awkwardness came as it was realised that the operation could not be mounted without substantial US support. President Obama found himself leading from behind, authorising an operation to help his allies avoid embarrassment. The Europeans just lack the ‘enablers’, the systems required to get forces into position and to support them over the course of an operation.

In addition, even if the US wanted to avoid any additional commitment, once allied forces became engaged in a wider war it is very hard to see how the US could stand aside, especially in the context of Russia breaching the terms of an agreement negotiated by Trump as well as Article V.

If reassuring Ukraine that its future security would be reinforced by the deployment of a multinational force made it possible for Zelensky to make difficult concessions, then Trump might be persuaded that some sort of American commitment was necessary.

But this leads to the second problem. For the same reasons that Zelensky wants such a force Putin would oppose it. Russia's Foreign Ministry spokesperson has said NATO troops in Ukraine would be ‘categorically unacceptable’ and provoke ‘uncontrolled escalation.’ Lavrov, while rejecting outright the idea of a peacekeeping contingent of ‘British and European forces’, has not quite ruled out some sort of peacekeeping force, although what he would have in mind would be traditional and toothless.

It is unlikely that any agreement with the Russians will authorise the introduction of any sort of force that would strengthen Ukraine’s defences. At most a basic ceasefire agreement would not preclude a force of some sort. One can imagine arguments in Europe that deciding on such a force after a ceasefire has been agreed would put it risk. It therefore makes sense to start talking about what can be done now, especially if as likely as not there will be no ceasefire. The discussion should be about how Ukraine can be supported now in an ongoing war, in ways which could continue in the event a ceasefire was agreed.

While there is much to be said for a large multi-national land force, and this should continue to be considered, there is little appetite for deploying one now when it would soon be fighting directly on Ukraine’s side. The idea of placing training missions inside Ukraine, making it easier to prepare troops for battle, is now getting more traction than before. This would be a more efficient way of conducting the training mission although the contributing governments would still need to work out how they would respond if their personnel were directly targeted by Russian missiles. There are still options other than land forces, which may be a hard sell politically, and could lead to a semi-permanent garrison. More might be done with air and maritime forces to protect international airspace and sea lanes. There were allusions to reasserting freedom of navigation in the Azov and Black seas in the recent UK-Ukrainian Treaty. This is all in addition to all that needs to be done to get weapons and ammunition to Ukraine, which is a vital source of pressure on Russia to end the war and is still the key factor in deterring a Russian return to aggression once the fighting stops.

It is important to keep in mind that the test of any deal, and associated security guarantees, is whether it allows a return to some sort of normality. Ukraine, anxious to recover from the war, wants to encourage businesses to invest so he much show that the country is sufficiently stable for them to be able to raise capital and get insurance. Without a deal, those businesses ready to take the risk to set up in Ukraine now, for both civilian and military purposes, would be reassured by special efforts being made to protect their facilities

So long as there is a possibility of a deal of some sort then the question of formal security guarantees will not go away, and Europeans will be expected to be part of the answer. The ideal would be a large deterrent force but the worst thing would be for European leaders to make more vague promises, or even firm commitments, and then fail to deliver. It is therefore important to be realistic about what might be involved. There will be no point in deploying such a force just to observe and report on any future Russian aggression. It must pose a real obstacle. Meanwhile there is much to be done to help Ukraine stabilise the front line, addressing gaps in its capabilities, all of which would make a ceasefire more likely, while building up Europe’s lacklustre defence capacity for a range of possible future contingencies.

I discussed some of the issues in this post with Mike Kofman in his new podcast (uploaded on 28 January) which can be found here. You will also be able to find here the first part of our conversation which discussed the overall state of the war.