United Kingdom has rejected Russia’s claims of inevitable military success in Ukraine, arguing that Moscow’s portrayal of steady advances across the battlefield is not supported by independent assessments of territorial gains and military losses.
Colonel Joby Rimmer, the UK Senior Military Advisor, challenged Russia’s account of the war during a recent meeting of the Forum for Security Co-operation (FSC), where he disputed claims by the Russian delegation that its armed forces were “steadily advancing on all fronts.”
Rimmer also rejected Russia’s description of Ukrainian military operations and counterattacks as “futile”, as well as Moscow’s assertion that Western military assistance to Kyiv has proved ineffective.
According to the British military adviser, those claims “do not withstand examination,” arguing that Russia’s battlefield narrative presented a picture of inevitable victory that was not reflected in available evidence.
Russia has continued to occupy significant areas of Ukrainian territory and has made localised advances in parts of the front. However, Rimmer argued that such tactical movements should not be interpreted as evidence of a decisive breakthrough or an inevitable Russian victory.
Russia claimed during the FSC that its forces had captured more than 5,300 square kilometres of territory and more than 220 settlements during 2026, including more than 670 square kilometres and 27 settlements in September.
Rimmer disputed those figures, citing independent open-source analysis that he stated found nothing close to the territorial gains claimed by Moscow.
The British assessment instead suggested that Russia had secured only a fraction of the territory it claimed, while Ukrainian counterattacks had enabled Kyiv to regain ground in some areas.
The Institute for the Study of War, according to Rimmer, has assessed that Ukrainian forces liberated 85 square kilometres during Operation VIVALDI alone.
Rimmer argued that the Russian presentation relied on interpreting selected tactical movements as evidence of a broader strategic advance.
“Interpreting selected tactical movements as ‘advancing on all fronts’ is not a military assessment,” he stated.
He added that there were “absolutely no indicators of a decisive Russian breakthrough,” arguing that Russia had not demonstrated the achievement of the objectives it initially set for its full-scale invasion.
The British assessment does not suggest that Russia has been militarily inactive. Rather, it distinguishes between localised territorial gains and the achievement of decisive strategic objectives.
Russia has continued offensive operations and retains substantial military capabilities, while Ukraine has faced continuing pressure along the front. Yet Rimmer argued that Ukraine’s ability to defend its positions and conduct counterattacks demonstrated that its armed forces had not collapsed.
“Russia has made localised gains, but minor tactical movements do not represent any sort of inevitable victory. Russian forces are not advancing everywhere. Ukraine has not collapsed, and the Ukrainian Armed Forces remain extremely capable of regaining territory, as the evidence shows on parts of the front.”
Colonel Joby Rimmer
Military Losses and the Continuing Role of Western Support
The disagreement over territorial gains extends into another central issue in the war: the effectiveness of Western military assistance to Ukraine.
During the FSC presentation, Russia reportedly used images of “decimated” Western military equipment to argue that military support provided to Kyiv had failed to alter the course of the conflict.
Rimmer rejected that interpretation, acknowledging that Western-supplied military vehicles can be destroyed in combat but arguing that individual equipment losses cannot, by themselves, demonstrate that a weapons system or broader military assistance programme has been ineffective.
“I know all too well from personal experience that Western vehicles are not invulnerable. Some of them may have been destroyed, damaged or abandoned, but the loss of individual systems is inherent in high-intensity warfare, and it does not establish that those systems have been operationally ineffective.”
Colonel Joby Rimmer
Rimmer noted that the appropriate comparison should instead consider the cumulative and proportional losses sustained by both sides.
He cited open-source project ORYX, which had by May 2026 visually confirmed Russian losses of 4,390 main battle tanks, 6,429 infantry fighting vehicles, 730 armoured personnel carriers and more than 2,000 other armoured vehicle variants.
Because the ORYX figures rely on photographic or video evidence, Rimmer argued that they represent a documented minimum rather than a complete account of Russian military losses.
“We have seen the defeat of thousands of Russian fighting vehicles, and these are documented losses, supported by photographic or video evidence, and therefore represent a minimum rather than a complete total.”
Colonel Joby Rimmer
The figures form part of the wider concerns over the role of Western assistance in Ukraine’s ability to resist Russia.
Since the full-scale invasion, Ukraine has received substantial military support from the United States, European countries and other partners. That assistance has included air-defence systems, artillery, armoured vehicles, ammunition and other military capabilities.
Moscow has repeatedly criticised Western military support and warned that continued deliveries could prolong the conflict. Western governments, meanwhile, have maintained that Ukraine has the right to defend itself against the invasion.
Rimmer argued that Russia’s own military behaviour undermines its claims that Western assistance has been ineffective.
“Russia’s own conduct contradicts its claims,” he stated, pointing to the resources Moscow continues to devote to locating Western-supplied systems, disrupting their supply routes and striking defence-production facilities in Ukraine.
He also indicated that Russia had threatened companies involved in defence-industrial cooperation with Ukraine but insisted that such threats would not change Britain’s policy.
At the same time, Rimmer stressed that British military assistance should not be interpreted as a desire for a wider confrontation between Britain and Russia.
The continued ability of Ukrainian forces to conduct counterattacks and long-range strikes has become an important element in assessments of the war’s trajectory.
According to Rimmer, Ukraine remains capable of defending the front, conducting counterattacks and striking military and war-supporting targets at considerable distances.
Ukraine’s defence industry has also continued to adapt, while its international defence partnerships have deepened.
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