Two 14-year-old boys were killed when an explosive device detonated in the evening in the Konotop district of Sumy Oblast, according to the statement by Oleh Hryhorov, head of the Sumy Regional Military Administration. The children encountered the dangerous device in a field, suffered severe injuries, and died at the scene, the statement said.

In 2022, Russian forces occupied parts of Sumy Oblast, but Ukraine liberated the region in April. Russia intensified its offensive again in 2025. Today, mines, unexploded ordnance and Russian drones shot down over the region pose a danger, as their warheads can detonate after falling. Overall, 146 children in Ukraine have suffered mine-related injuries, former Interior Minister Ihor Klymenko reported in April. For example, two months ago, an 11-year-old boy and a 15-year-old boy in Sumy Oblast were injured when an explosive device detonated.

Hryhorov expressed his condolences to the parents and relatives of the victims and urged people to remain cautious:

“Please be as careful as possible and remind children: do not approach unknown or suspicious objects, touch them, or try to move them. Take care of yourselves and your loved ones,” Hryhorov said.

Demining efforts continue in Sumy Oblast

On 24 February 2022, Russian forces entered the territory of Sumy Oblast. The first battles in the region took place that same day. In particular, Russian forces attempted to break through to Sumy, but Ukrainian troops repelled the offensive. On 11 April 2022, Ukraine restored control over the entire Sumy region.

As early as 7 June 2022, deminers were working in the Konotop, Sumy, and Okhtyrka districts, according to the Government Portal. That day, they surveyed areas and neutralized explosive devices.

The work of deminers remains deadly dangerous. In September 2024, two pyrotechnicians from Dnipropetrovsk Oblast were hit by a mine while demining Sumy Oblast: one died, while the other was hospitalized. In July 2025, deminer Oleh Petrenko was killed during humanitarian demining operations in Shostka District when a Russian FPV drone detonated, the State Emergency Service of Ukraine reported. Another pyrotechnician was injured, the statement said.

Nevertheless, the work continues despite the danger. In 2025, State Emergency Service deminers in the Sumy Oblast found and neutralized 5,283 explosive devices, the agency said in April. Sumy Oblast ranked sixth among all Ukrainian regions by this figure.

Twenty-two percent of Ukraine’s territory is potentially contaminated with explosive devices — more than 133,000 square kilometers, former Interior Minister Ihor Klymenko reported in April this year. Since the beginning of the full-scale invasion, State Emergency Service and National Police deminers have surveyed more than 248,000 hectares of territory and found more than 1 million 112 thousand explosive devices, the statement said.

Ukraine's Vivaldi counteroffensive rolled back a Russian advance north of Lyman in Donetsk Oblast. However, Moscow shifted part of its forces south, Roman Pohorilyi, co-founder of the Ukrainian battlefield mapping project DeepState, told Radio NV. Russian troops are now infiltrating Mykolaivka, a key strongpoint on the approach to the fortress city of Sloviansk, Pohorilyi said.

The halted advance was one arm of Russia's plan to encircle Ukraine's Donetsk fortress belt—the fortified cities of Sloviansk, Kramatorsk, Druzhkivka, and Kostiantynivka. Pohorilyi warned that losing Mykolaivka would create serious problems for Sloviansk's defenders. Russia is still pressing toward Dobropillia on the belt's southwestern flank.

Pohorilyi said Russia formed a "claw" north of Lyman by exploiting Ukrainian brigades short of personnel and pushing small groups into their lines. Ukraine's Third Army Corps stabilized the area, built up forces, and counterattacked. The push "multiplied all [Russia's] previous efforts by zero," he said.

Russian forces had repeatedly tried to capture or bypass Lyman, Pohorilyi said. Russian groups still infiltrate the approaches to the city, although Ukrainian forces have stabilized the situation there.

The corps says Vivaldi's first two phases regained control of 125 square kilometers, including 50 that had been under Russian occupation. It reported liberating Shandryholove and Derylove, securing Drobysheve, and inflicting more than 3,000 Russian personnel losses. Those battlefield figures have not been independently verified.

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Pohorilyi noted that the area around Mykolaivka had, until recently, been under the responsibility of Ukraine's 11th Army Corps and is now under the Third Army Corps.

Ukrainian troops must now find and stop infiltrating Russian groups before they establish control, he said. Personnel shortages on the Lyman axis persist, although he said reinforcements are being distributed more evenly.

Operation Vivaldi and the wider fight for Donetsk's fortress belt

The Third Army Corps first disclosed Operation Vivaldi on 15 September after conducting the counteroffensive north of Lyman under information silence. Commander Andrii Biletskyi said the announced gains were only the first phase; the corps said its attacks had disrupted Russian supply routes.

A 60th Mechanized Brigade captain said Ukrainian units quietly assembled near Derylove and Drobysheve, then struck Russian drone launch sites at planned times so infantry could advance. The corps disclosed a second phase on 20 September.

Farther southwest, Dobropillia faces even heavier pressure, Pohorilyi said. Russia has concentrated large forces there and is pushing with relentless infantry across a wide front, backed by thousands of drones each month—reconnaissance, strike, FPV, and Lancets—with numbers still rising. Russian troops are moving on settlements south of Dobropillia to establish a strongpoint and push deeper into Donetsk Oblast.

The pressure is not new: Biletskyi said Ukrainian troops halted a Russian incursion there last year. After Moscow claimed on 22 September to have encircled the town, the Institute for the Study of War found no evidence to support the claim.