Consolidating Europe’s Eastern Frontiers: the Options for Ukraine and the Continent

Almost two months into President Trump’s tenure in the White House, his promised and highly publicised quick resolution of Russia’s war in Ukraine remains as unclear and confusing as ever. Following a controversial Oval Office meeting with President Zelensky, Ukraine took steps to mend relations with the US administration, first proposing a staged ceasefire, later accepting a US proposal for a 30-day ceasefire and most recently a ceasefire on energy infrastructure.

Moscow’s position – that it seeks a comprehensive agreement rather than interim measures – is a familiar tactic. Russia wants to signal that it is in no hurry, while continuing to use violence as leverage against Ukraine and, more importantly, against a US administration eager for a quick resolution. It remains highly uncertain whether any ceasefire will actually take hold and be upheld – and, crucially, whether the US will press for more concessions from Russia or from Ukraine.

For Ukraine, the prospect of a sustainable end to the war is undoubtedly a commendable goal. There is no doubt that the country is suffering gravely from the violence, and peace remains its greatest aspiration. However, the credibility and reliability of any peace arrangements are absolutely critical to ensure – peace will only be as robust as the means by which it is protected.

Russia’s Approach to Negotiations

Amidst the uncertainty and contradictions surrounding the US-led peace efforts, as well as Washington’s shift to deprioritise European security, Russia’s fundamental objectives remain unchanged. Intelligence specialists and analysts widely agree that Russia continues to pursue its original strategy of undermining Ukraine and Europe’s security architecture. Every action Moscow takes is ultimately geared towards achieving these enduring goals.

Feeling relatively secure in its current position and ready to exploit the US administration’s stated commitment to ending the war through diplomacy, Russia has two options. Either continue hostilities or attempt to gain an advantage through diplomatic manoeuvres. Any diplomatic breakthrough that Russia achieves will, however, be incorporated into its broader grand strategy. There is a high probability that the Kremlin will then use any cessation or reduction of hostilities to prepare for the next phase of its military campaign. If the US manages to broker a comprehensive ceasefire, Russia will likely treat it as an operational or strategic pause, a window of opportunity to strengthen its position before launching a decisive strike.

Should this plan succeed, a renewed Russian offensive could deal a devastating blow both to Ukraine and to Europe’s security. Moscow views the current situation as a historic opportunity, where a convergence of favourable conditions creates the perfect storm. The US administration no longer considers the Russian regime an outright adversary and has repeatedly failed to condemn its numerous war crimes and genocidal policies. It refuses to identify Russia as the aggressor and openly discusses "enormous economic opportunities" and the prospect of normalisation – something that, until now, would have been unthinkable.

The United States Risks Facilitating Further Russian Aggression

As the cornerstone of NATO and European security, the United States’ ambiguous position creates deep uncertainty about its response should Russian aggression expand into other European countries. If Moscow manages to negotiate the lifting of sanctions in exchange for a ceasefire, its militarised economy will quickly regain strength, and in a very short time Russia could once again emerge as a formidable military force.

Today, Russia is exhausted and severely weakened by its military failures in Ukraine. It lacks the ability to amass the necessary mass of equipment, and it is visibly running out of personnel. Equally significant is the fact that its warfighting methods are no longer effective – even the brutal human-wave assaults that proved successful in 2023 and 2024 are now failing to deliver decisive results.

A ceasefire would provide Russia with the time it needs to reassess its approach and rebuild a military force based on new operational concepts. The Russian war economy is too deeply entrenched to be quickly dismantled or converted back to a civilian model, but it is unlikely that de-escalation is even a strategic objective. Instead, Moscow is likely to be motivated by a drive to compensate for past underperformance coupled with a sense of strategic opportunity created by US policy shifts. A ceasefire is, therefore, likely to lead to a dramatic new phase of Russian militarisation.

Historical precedents support this possibility. Iraq’s military re-emerged in 1991 after enduring the hardships of the Iran-Iraq War, while revanchist ambitions fuelled Nazi Germany’s military expansion following early setbacks. Russia may well follow a similar trajectory, using the lessons of this war to rebuild an even stronger force and emerge from its war of attrition in Ukraine with a revamped military – its own version of a new ‘Grande Armée’.

The mere presence of such a revitalised Russian force along Europe’s borders would constitute an existential threat to its neighbours, granting Moscow immense leverage over the region. Beyond direct military pressure, Russia would certainly employ a full spectrum of hybrid warfare tactics, including political coercion, cyber operations, and economic manipulation. It could also destabilise multiple regions, including the Arctic, the Baltic, Balkans, Poland, the Black Sea, and the Mediterranean. Ukraine, of course, would remain at the highest risk, with a renewed Russian offensive highly probable.

If the Black Sea Straits are reopened, it would enable Moscow to rebuild its Black Sea Fleet, once again posing a threat to freedom of navigation, endangering Ukrainian ports, and extending the threat to Moldova from the maritime domain.

The Imperative of Building European Deterrence

The only way to prevent this scenario is to recognise the severity of the threat and build a force capable of making Russian aggression futile. Given Russia’s demonstrated willingness to absorb significant losses, deterrence by punishment is unlikely to be effective. Instead, only deterrence by denial – ensuring that any future attack would be impossible or overwhelmingly costly – can secure lasting peace in the region.

This deterrence strategy must no longer be viewed as simply assisting Ukraine in isolation from NATO Europe. Russia has long been recognised as a pan-European threat – while Ukraine remains Putin’s primary focus, it is not his only target. Therefore, deterrence must be pan-European, treating Ukraine’s security as an integral part of the broader European defence architecture. While the Europeans are trying to persuade US administration to provide them with a backstop, the probability, extent and reliability of such support are unclear.

As the existing structures of NATO and the EU cannot serve as the foundation for this effort, the only viable solution is the formation of a coalition of the willing, committed to ensuring that Russia is permanently denied the ability to wage expansionist war. Security arrangements must incorporate all fundamental elements of effective deterrence: they must be credible, rooted in capabilities proportionate to the threat, and clearly communicated to both Russia and the wider international community.

Moreover, they must be built on concepts of future warfare rather than outdated strategies. Legacy methods will prove ineffective against a Russian force that has adapted its doctrine based on lessons learned and technological advancements.

One of the key lessons from three years of war is that the most effective way for coalition governments and militaries to engage fully is to launch a dedicated operation aimed at countering the risk of a renewed Russian attack. Such an operation should be coordinated through a joint headquarters, with each participating state undertaking the necessary organisational steps within their respective ministries of defence to ensure its implementation. Those familiar with military structures understand that only an active, ongoing operation enables proper resource allocation, rapid decision-making, and the deployment of dedicated personnel. Military actions must be governed by structured operational planning, integrated command structures, and strict operational timelines.

For the purposes of this article, such an operation will be referred to as the Eastern Frontier Operation.

Integrating Ukraine’s Defence into European Deterrence

The coalition participants must recognise that Russia will be vocally opposed to this initiative from the outset. Moscow has a well-established pattern of justifying its aggression through victim-blaming narratives, claiming that the ‘true causes’ of the war lie elsewhere. Every instance of international military cooperation with Ukraine has been framed by Russia as a provocation or justification for its own aggression.

Policymakers must be fully aware of these tactics, resist falling into Russia’s narrative traps, and remain firm in establishing robust security arrangements. Any form of self-deterrence in setting up these measures would weaken the region and increase the risk of renewed hostilities.

The Ukrainian component of the Eastern Frontier Operation must be designed to enable Ukraine to withstand and successfully repel a potential future full-scale Russian attack. This comprehensive defensive capability should integrate the Ukrainian defence forces, the country’s full mobilisation potential, and dedicated resources provided by allied nations.

The operational framework must be structured as a multi-domain effort, encompassing the generation, sustainment, and deployment of capabilities across land, air, maritime, cyber, and information domains. Implementing this strategy will be an extremely complex undertaking, requiring meticulous planning and substantial contributions from coalition participants. As of now, we can identify seven potential formats in which Western forces could participate in the operation.

The most committed form of participation would be the direct deployment of troops in Ukraine, with active engagement in the event of renewed Russian aggression. This scenario, often referred to as ‘boots on the ground’, has been widely debated. The presence of land forces may, however, be less effective compared to other strategic options. A more impactful approach could be ‘airmen boots’ – the deployment of aerial and air defence units to protect Ukrainian airspace from Russian strikes.

One of the most compelling alternative proposals is a ‘Sky Shield over Ukraine’, a concept involving the air policing of Ukrainian airspace, particularly over its western and central regions, to defend against Russian missile and air strikes. This initiative could establish a large safe zone, enabling social stability and economic recovery, while allowing the Ukrainian Air Force to concentrate its resources on defending the eastern front.

A third option for Western assistance could be monitoring the ceasefire. A dedicated monitoring mission, equipped with advanced technology and surveillance tools, would be essential to maintaining constant situational awareness. Past phases of the Russo-Ukrainian war have been marked by repeated ceasefire violations and mutual accusations, which the OSCE Special Monitoring Mission failed to address effectively due to its limited access and inadequate equipment.

A fourth option involves remote capability support, including the provision of real-time intelligence, training, technical advice, and maintenance. This could also extend to remote operations, such as defensive cyber operations and information warfare, which would strengthen Ukraine’s ability to counter Russian aggression without requiring a direct Western presence.

A fifth option is the creation of strategic reserves for Ukraine in the form of pre-positioned military assets and capabilities. These resources would be immediately available, stored in secure locations in Eastern Europe, and operated by the coalition headquarters. Such facilities could function as a network of depots, housing weapons, ammunition, and essential military equipment near Ukraine’s borders. In the event of renewed hostilities, these reserves would enable the rapid mobilisation and rearmament of Ukrainian forces, allowing them to counter a large-scale Russian offensive effectively. These warehouses would store additional armaments, spare parts, ammunition, expendables, communication systems, and other critical supplies.

Another crucial form of support would be the direct provision of modern Western equipment to Ukraine’s defence forces. The most pressing requirement is sufficient ground-based air defence systems and advanced tactical aviation to prevent Russia from establishing air superiority. If Ukraine achieves air dominance over its own territory, the likelihood of a renewed Russian offensive will be significantly reduced.

Additionally, Ukraine must have long-range missile systems capable of striking deep into enemy territory, targeting command and control centres, logistics hubs, and supply lines. Precision strikes on these key assets would significantly weaken Russia’s capacity to sustain large-scale military operations.

While warfare technologies continue to evolve, certain core military assets remain indispensable. Ukraine will continue to require artillery, MRAPs (mine-resistant ambush-protected vehicles), and firearms, all of which are essential for sustained ground operations.

Finally, the allies can further strengthen Ukraine’s long-term defence capabilities by enhancing support for its domestic defence industry, particularly in areas where Ukraine is already technologically advanced. The development of Ukraine’s defence sector is well underway and should be expanded and accelerated. This includes investment in unmanned systems, electronic warfare technologies, and other critical defence innovations.

Building a force capable of credibly deterring and repelling Russian aggression will be a formidable challenge. However, the coalition’s collective technological, industrial, and economic resources far exceed those of Russia, making this goal fully achievable. Through joint efforts, a unified threat assessment, decisive action, and resilience against Russian intimidation, the coalition can forge a security framework that ensures long-term peace and stability across the region.

© Andriy Zogorodnyuk, Alina Frolova and Oleksandr Khara, 2025, published by RUSI with permission of the authors.

The views expressed in this Commentary are the authors’, and do not represent those of RUSI or any other institution.

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