On an unremarkable day in May, in near-total secrecy, Ukraine quietly launched one of its most audacious fightbacks against Russia to date.

The first rumours came over summer. A few analysts and military bloggers noticed more movement than usual at a crucial point near Lyman, a city in Ukraine’s Donetsk region. Ukrainian forces seemed to be counter-attacking there, where over the past year, Russia had been making slow but steady gains.

Ukraine played it down as “limited in scope” and battlefield trackers logged little change in territory. But by the start of September, Russian milbloggers were nervous, describing a difficult situation on the front.

“It seems to me that the Ukrainians have been conducting a counteroffensive for 2.5 months, which our command is trying not to notice,” Anatoly Radov, a prominent pro-war commentator, said on 6 September.

It was only on 15 September that Ukraine finally acknowledged something large-scale had been taking place. Andrii Biletskyi, commander of the 3rd Army Corps, announced that Ukrainian forces – under maximum operational secrecy – had been conducting a groundbreaking offensive called “Operation Vivaldi”.

“A devastating blow has been dealt to the combat effectiveness of the Russian 20th and 25th Armies,” Biletskyi said.

For months, Moscow had been pushing to encircle Ukraine’s fortress belt cities, including major targets Sloviansk and Kramatorsk, and in January its troops were at the outskirts of Lyman, a crucial logistics, road and rail hub. Its capture would have handed Moscow a staging base for an offensive against Sloviansk. Vivaldi has blunted the northern claw of that pincer movement.

“Vivaldi is critical for Ukraine war effort overall,” Mykola Bielieskov, a research fellow at the National Institute for Strategic Studies think-tank in Kyiv, told The i Paper.

The near-total secrecy of the offensive, not to mention its tactics and use of robot technology, have reversed months of Russian gains, despite Ukrainian manpower disadvantages and the difficulties posed by the drone-dense kill zone.

The Russian delusion factor

Under a media blackout, Ukraine has seized 147 square kilometres of territory during Operation Vivaldi, according to the Washington-based Institute for the Study of War (ISW).

Ukraine’s real-time gains could be even higher. The announced advances are likely months-old and details are still being carefully controlled by Ukrainian officials. The ISW has said its own mapping methodology is “likely underestimating the extent of Ukrainian gains”.

It added that since March, Russia’s rate of seizing territory from Ukraine has been significantly declining – or even negative.

Ukraine’s information blackout appears to have played a major part in its success. “Often offensives are given away before they start, giving Russia time to move units around and get into a position to counter the advance. So, secrecy in the lead-up is really important,” said Sam Cranny-Evans, an associate fellow in military science at the Royal United Services Institute. “In some cases, it has taken the Russians a while to realise that they were under attack or the scale of the advance.”

Biletskyi warned those watching events unfold not to share “spoilers” that could imperil the ongoing operation. “Vivaldi, as is well known, has four seasons,” he warned, in reference to the Italian composer’s famous violin concerti. Biletskyi announced the completion of Operation Vivaldi’s second and third “seasons” towards the end of September.

“Operational security is enormously important in warfare,” Scott Boston, a senior defence analyst at the Rand Corporation, told The i Paper. “The Russians in particular have a lot of reconnaissance capabilities, including drones, and the more they are fixated on Kostyantynivka or Kramatorsk or Dobropillia, the less they might be noticing and responding elsewhere where there’s a successful operation going on.”

Bielieskov has claimed that – a Soviet military doctrine of deception – helped Ukraine take advantage of poor communication within the Russian military.

“Russia has repeatedly shown an unwillingness to report bad news up the chain of command,” said Boston. “When that happens at multiple levels it really dilutes the effect of their potential advantages.”

The extent of that culture was demonstrated last month when Vladimir Putin claimed that Russia had captured the city of Svyatohirs’k, west of Lyman and far behind Ukrainian lines. Shortly afterwards, Biletskyi posted a video of himself in central Svyatohirs’k.

“I want to address the Russian military and military political leadership. Take off your clown noses and colourful wigs. Stop making fools of yourselves,” he said.

Russian military bloggers have shown their frustration over Moscow’s detachment from the reality on the ground. Radov published a recording – now deleted – which he said he sent to a Russian officer, asking: “Is there a guy among you – for f**k’s sake – who can tell Uncle Vova [Putin] that his picture isn’t actually all that pretty… we’re totally f**ked on the Lyman front.”

Tactics and technology are changing the game

During Operation Vivaldi, Ukraine has deployed innovative battlefield tactics, including novel uses of bomber drones, kamikaze robots and electronic warfare (EW). Robert G Rose, chief research officer at the Modern War Institute at West Point, the US military academy, said: “The Ukrainian corps performed this masterpiece by achieving drone dominance over Russian forces.”

Ukraine’s 3rd Army Corps said EW units had disrupted more than 20,000 Russian drone missions by detecting, jamming and suppressing their signals to conceal Ukrainian attacks.

“For a long time, Ukraine has been building up its EW capabilities, devolving them to the lowest echelons possible and connecting them to other systems as much as possible,” said Cranny-Evans.

Meanwhile, Ukraine’s Unmanned Systems Forces have saturated Russian rear areas, using drones like the AI-enabled Hornet to enable 30-200-kilometre strikes against logistics, command posts, drone control centres and river crossings.

Ukraine has also sent in heavy bomber drones to air-drop ground robots equipped with grenade launchers miles behind Russian lines, and claims to have filled two Soviet-era armoured personnel carriers with explosives, converting them into giant robotic systems to slam into Russian positions.

“They have changed the game by developing a whole new approach that focuses on their relative strengths in robotics systems,” said Boston.

According to Bielieskov, Vivaldi has “proved that the same technology that led to stalemate in 2023-25” is useful for bringing more movement to the battlefield. “The trick is quality of training and leadership of officers,” he said.

What Vivaldi means for the war

Ukraine claims Russian losses, both dead and injured, across the three announced seasons have so far totaled 5,000, with hundreds taken prisoner. However, the latest offensive is unlikely to change the course of the war.

“In terms of the entire size of the occupied territories in Ukraine, it is fair to say this is a relatively small area,” Boston said. “However, given the circumstances and the overall Russian advantage in men and materiel, it is impressive.”

By reversing months of Russian gains, Vivaldi also represents a setback for Putin’s war aims of seizing the Donbas.

“Oleksandrivka, Vivaldi and various others have successfully pushed Russian units back and frustrated some of their goals for the year,” said Cranny-Evans. However, he said it was important to balance this out. “Whilst it is good and encouraging to see Ukraine advancing, the Russians are still advancing in some areas, and their strikes against Ukraine’s power infrastructure and even its data centres are really taking a toll.”

Rose added that to alter the course of the war, “Ukraine will have to envision Vivaldi on a grander scale… only such a decisive Ukrainian battlefield victory will force Russian President Vladimir Putin, Russian elites and the common Russian soldier to reappraise the war”.

Even so, as the Vivaldi offensive moves into its fourth season, Biletskyi warned that the “music continues”.