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.

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Ukrainian push into Russia is 'catastrophic' for Putin's plans, former U.S. ambassador says

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Ukrainian push into Russia is 'catastrophic' for Putin's plans, former U.S. ambassador says

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 Kurskincursion, the Ukrainian army has captured 1,263 square kilometresand 93 settlements, Ukraine's top military commander Gen. Oleksandr Syrskyi said Tuesday.

Ukraine reaching 'set goals': Zelenskyy

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

Zelenskyyhas 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 Tassreported 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 themhave been hospitalized with injuries, according to Tass, citing local officials.

Ukraine's Army General Staff claimed responsibility Sunday for attacking the oil depot, which was used to supply the needs of Russia's army.

Putin accuses Ukraine of 'trying to destabilize'

Russian President Vladimir Putin accused the Ukrainians of "trying to destabilize our country," vowing to"punish the criminals."

Ukraine's incursion has exposed Russian vulnerabilities according to analysts and Ukrainian officials.

Zelenskyy said Monday that he believes Ukraine's actions would help to dispel Western fears of offering more robust military aid to Kyiv. Some allies have been handing over weapons slowly and imposing limits on how they can be used, fearing that crossing a Russian "red-line" could lead to escalation even nuclear escalation.

In Washington, U.S. Maj.-Gen. Pat Ryder, the Pentagon press secretary, told journalists Tuesday that the U.S. is "always looking at ways that we can expedite delivery of capabilities to the Ukrainians."

Ryder also said the U.S. had "seen indications of Russia moving ...a small number of forces into Kursk" to respond to Ukraine's offensive there.

Much remains unknown about Ukrainian operations in Russia but satellite images provide some clues.

Pontoon bridges temporary bridges used by militaries when formal bridges are blown out could be seen in the satellite images provide by Planet Labs PBC in two different positions along the Seym River in recent days. The pontoons likely were built by Russian troops trying to supply forces around the Ukrainian advance.

One pontoon bridge appeared along the serpentine path of the river between Glushkovo and the village of Zvannoye on Saturday, but not in images taken Monday. On Monday, smoke could be seen rising along the banks of the river nearby typically the sign of a strike.

The Institute for the Study of War, a Washington-based think-tank, said on Tuesdaythat Ukrainian forces in Kursk"appear to be continuing efforts to strike Russian pontoon bridges and pontoon engineering equipment."

Pokrovsk under pressure

Meanwhile along the frontline in eastern Ukraine, Russia continued to bear down on the city of Pokrovsk, one of Ukraine's main defensive strongholds and a key logistics hub in the Donetsk region, forcing Kyiv's forces to pull back and civilians to flee their homes.

Russia's relentless six-month slog across the region following the capture of Avdiivka in Februaryhas cost both sides heavily in troops and armour.

Russia wants control of all parts of Donetsk and neighbouring Luhansk, which together make up the Donbas industrial region.

AlsoTuesday, four teenagers were injured after Russian forces struck a park in Ukraine's southern Zaporizhzhia region, local Gov. Ivan Fedorov said on Telegram. A 15-year-old later died in hospital, according to the office of Ukraine's prosecutor general. It wasn't immediately clear what weapon was used.

In the neighbouring Kherson region, Russian strikes wounded four men and a 14-year-old boy, local authorities reported.

In Russia's Belgorod region, a Ukrainian drone attack injured a civilian, according to local Gov. Vyacheslav Gladkov.