Russia’s Aggression in Ukraine Will Persist Through 2026

As Russia’s full-scale invasion of Ukraine enters its fifth year both Russia and Ukraine are under increasing strain. For Ukraine the question is whether it can bring about a mutually hurting stalemate leading to a ceasefire. For Russia, the plan remains to exhaust Ukraine’s capacity to resist. Under current conditions, however, it is more dangerous in both Kyiv and the Kremlin to stop fighting.

International attention has become fixated on the negotiations imposed on the parties by the US. Washington has worked its way towards offering Ukraine security guarantees if Ukraine is prepared to abandon the remainder of Donbas. At the same time the US’s rhetoric towards Europe and its National Security Strategy has undermined confidence that these guarantees would be honoured, while the territory that Ukraine is being asked to evacuate comprises its defensive belt, such that withdrawal would require its forces to move onto unprepared and indefensible terrain. The result is that any collapse of a ceasefire during implementation would leave Ukraine in a much-weakened position militarily. In short, the US has a bad offer.

The Russians, meanwhile, are maintaining a maximalist position. The Russians believe they can sustain the war into 2027 and perceive the ongoing process of negotiations as a vehicle for driving a wedge into the transatlantic alliance. Europe is rearming, but it is taking time, such that many European states feel a sudden ceasefire on unfavourable terms would expose the continent to grave risks. The White House wants a ceasefire quickly to pave the path towards renewed economic engagement with Russia. But with Russia spending approximately $500 billion a year on defence (when measured by purchasing power parity) and with little prospect of this shrinking in the event of a ceasefire, the removal of sanctions is perceived in Europe to be highly dangerous. The US and EU are therefore diametrically opposed in their objectives.

At the same time, the US has halted meaningful military assistance to Kyiv, even obstructing European purchases of US materiel through the PURL framework. Although European defence industry is expanding production Kyiv remains short of critical supplies. European unity is also under sustained attack from Russian subversion, and the combination leaves the Kremlin hoping that current levels of support for Ukraine may fade, directly impacting the battlefield situation.

Conditions for Russia and Ukraine

Russia has succeeded in destroying a significant proportion of the Ukrainian energy grid. Although this is most acutely felt today during the winter’s low temperatures, it will have a sustained impact on government services, education and industry. The result will be increasing numbers of Ukrainian refugees heading for Europe. Russia will use this issue to both exacerbate hostility to Ukrainians – playing on European concerns about economic migration – and endeavour to distract Europe from the foundations of Ukraine’s resistance: military-technical assistance.

For the past year, Russian gains have been enabled by the growing lethality of Russian fires and dwindling Ukrainian troop strength allowing Russia to persistently infiltrate and thereby undermine Ukrainian defensive positions. Over the course of 2025, however, some of Ukraine’s better units worked out how to conduct offensive operations under modern conditions. This has enabled successful counter attacks in Kupiansk and in the South. The question for Kyiv is whether the tactics of these units can be taught more widely across the front. Fixing Ukraine’s training process is the key to addressing the challenge of force generation and thereby bolstering the strength of units at the front such that Russia cannot continue its infiltration tactics when vegetation returns in the Spring.

Russia is likely able to maintain its current rate of recruitment, despite the punishing rate of casualties inflicted by Ukrainian fires, although a higher proportion of those brought into the force are mobilised reservists or coerced rather than volunteers. If Russia is making steady or accelerating gains the Kremlin will sustain the effort. If progress slows significantly, Putin’s perception of his prospects may shift as political risks at home expand.

A critical variable is how much damage Kyiv and its partners can inflict on Russia while the Ukrainian Army holds the front. Kyiv’s long-range strike drones are having a diminishing impact as Russia expands the density of its passive defences. But long-range cruise missiles offer the prospect of many more targets being struck. Separately, European states have laid out the legal basing for the systematic interdiction of Russia’s shadow fleet but have so far avoided enforcing such measures. The Russian economy can keep up the war, but as reserves dwindle and debt grows, it also becomes more vulnerable to shocks. The question is whether Europe is prepared to apply the pressure.

For Kyiv, therefore, a ceasefire risks ceding militarily critical ground with little prospect of enduring security. Politically, this would be a hard sell for Zelensky at home. And so Ukraine is likely to fight on and must show Russia it can fight on for an extended period if the Kremlin is to abandon the hope of exhausting Ukraine in the medium term. The Kremlin, meanwhile, believing it may achieve militarily what is on the table today through diplomacy, and perceiving its leverage as building over time, will keep the negotiations going but in essence string along the process. Unless Russia suffers significantly higher casualties or greater economic pain its aggression will continue.

For Europe, therefore, the three tracks of policy must remain the aggressive countering of Russian subversion, the sustained supply of the Ukrainian military with arms and an active policy to impose costs on Russia. The US will endeavour to accelerate the end of the conflict. But having severed most support to Ukraine, undermined the trust of its allies and made clear that it will avoid applying any serious pressure on Russia, Washington is rapidly bleeding leverage. If a US-imposed deal materialises, the durability of any subsequent peace is doubtful.

© RUSI, 2026.

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