Russian sources say Ukraine has hit all three bridges over the Seym River

Ukrainian forces have either destroyed or damaged all three of the bridges over the Seym River in western Russia, according to Russian sources, as Kyiv's incursion into western Russia entered its third week Tuesday.

Kyiv's incursion into Russia's Kursk region is changing the trajectory of the war and boosting morale among Ukraine's war-weary population, though the ultimate outcome of the incursion — the first attack on Russia since the Second World War — remains impossible to predict.

Even as Ukraine hails its success on Russian territory, the Russian push in eastern Ukraine is poised to claim another key centre: the city of Pokrovsk.

Ukraine's attacks on the Seym River bridges could potentially trap Russian forces between the river, the Ukrainian advance and the Ukrainian border. Already they appear to be slowing down Russia's response to the Kursk incursion, which Ukraine launched on Aug. 6.

Over the weekend, Ukraine's air force commander posted two videos of bridges over the Seym being hit, and satellite photos by Planet Labs PBC analyzed Tuesday by The Associated Press confirmed that a bridge in the town of Glushkovo had been destroyed.

A Russian military investigator confirmed Monday that Ukraine had "totally destroyed" one bridge and damaged two others in the area. The full extent of the damage remained unclear.

"As a result of targeted shelling with the use of rocket and artillery weapons against residential buildings and civilian infrastructure in the Karyzh village ... a third bridge over the Seym River was damaged," the unnamed representative for Russia's Investigative Committee said in a video published on the Telegram channel of Russian state TV anchor Vladimir Solovyov.

Russian military bloggers Vladimir Romanov and Yuri Podolyaka and several high-profile pro-war Telegram channels in Russia also claimed that the third bridge had been targeted and damaged. Podolyaka's post was shared by Roman Alekhin, an advisor to Kursk's acting regional governor.

Since the start of the Kursk incursion, the Ukrainian army has captured 1,263 square kilometres and 93 settlements, Ukraine's top military commander Gen. Oleksandr Syrskyi said Tuesday.

Following a meeting with Syrskyi, Ukrainian President Volodymyr Zelenskyy said the Ukrainian army was achieving "set goals" in Kursk.

Zelenskyy has said the operation is aimed at creating a buffer zone that can prevent future attacks from Russian territory, and that Ukraine is capturing a large number of Russian prisoners of war that it hopes to exchange for captured Ukrainians.

The Russian state news agency Tass reported that 17 people have died and 140 have been injured in Ukraine's incursion, citing an unnamed source in the Russian medical service. Russia's Ministry of Emergency Situations said Tuesday afternoon that more than 500 people had left dangerous areas in the Kursk region over the past day. More than 122,000 people have been resettled since the Ukrainian attack began, it said.

In another example of Ukraine taking the war to Russian soil, a massive fire burned for the third consecutive day after an oil depot was hit by Ukrainian drones.

The fire at the depot in the town of Proletarsk burned across an area of a hectare, according to Russian state news agencies. There were 500 firefighters involved in the operation, and 41 of them have been hospitalized with injuries, according to Tass, citing local officials.