At the same time, Ukraine scored a high number of hits on Russian energy infrastructure and occupied Crimea, suggesting that its strategy of degrading Russian air defences is working.

Russian assaults focused on central and southern Donetsk – from areas west of Bakhmut, which fell in May last year, to areas west of Avdiivka, which was lost in February, down to areas west of the city of Donetsk, which pro-Moscow separatists have controlled since 2014 – a line about 130km (80 miles) long.

Russian forces have pressed their advantage in these areas to prevent Ukraine from digging entrenched defences, and they have inched forward for months, swallowing settlements at a staggering cost to their own troops.

British military intelligence estimated that Russian casualties in May and June reached record daily highs of about 1,200 – about 70,000 soldiers for just those two months.

In the past week, the tempo of Russia’s westward crawl has increased and included two battalion-sized assaults that the Institute for the Study of War (ISW), a Washington-based think tank, said Russia has not mounted since the battle for Avdiivka in October.

It appeared that Russia’s strategy was to cut off two highways – one supplying Ukraine’s garrison in Vuhledar in southern Donetsk and the other supplying garrisons in Chasiv Yar and Toretsk in central Donetsk.

Russia mounted a battalion-sized assault involving 200 soldiers southwest of Donetsk city on July 24. It was supported by 11 tanks, 45 armoured fighting vehicles and 12 motorcycles. Its apparent purpose was to seize the T-0524 highway supplying Vuhledar. Ukrainian forces stopped it, destroying six of the tanks, seven armoured vehicles and all 12 motorcycles.

Then on Monday, Russia tried again, mounting another battalion-sized assault in the same area, this time with 10 tanks, 47 armoured vehicles, 10 motorcycles and a buggy. Again Ukraine stopped the assault, striking eight tanks, a dozen armoured vehicles and nine of the motorcycles plus the buggy.

“The Russian military command’s willingness to accept costly armoured vehicle losses without conducting a large-scale, multi-directional offensive operation or making operationally significant advances in western Donetsk Oblast will likely burden the Russian military in the long-term,” the ISW said.

On Friday, Russian troops seized the villages of Prohres, Yasnobrodivka and Lozuvatske, all within 15km (9 miles) of each other, extending a salient west of Avdiivka. That brought them within 7km (4 miles) of the T-0504 highway, extending from Pokrovsk to the garrisons of Chasiv Yar and Toretsk.

“If the armed forces of Ukraine fail to stabilise the situation, Russian troops across a wide swath of the front may be able to reach the Pokrovsk-Kostyantynivka highway – the main supply line for the [Ukrainian troops] in Chasiv Yar and Toretsk – in a matter of weeks,” wrote Meduza, an independent Russian newspaper banned by Moscow.

On Friday, Russian troops reclaimed Robotyne, a town in the southern region of Zaporizhia that Ukraine had fought hard to reclaim in its 2023 counteroffensive.

On Saturday, Russian troops entered Krasnohorivka, west of Donetsk city, and on Tuesday claimed to have captured two more villages, Pivdenne and Vesele, west of Avdiivka.

But the most significant reports were Russian claims to have advanced into Chasiv Yar, a strategic height that would give them access to flatlands leading to the cities of Sloviansk and Kramatorsk, which form the backbone of Ukraine’s defence in Donetsk.

Ukrainian troops have so far managed to keep Russian forces on the eastern side of the Siversky-Donetsk canal, which runs through Chasiv Yar, but on Monday, Russian reporters said soldiers had broken through at a point north of Chasiv Yar where the canal runs underground. Those reports remained unverified.

On Friday and Saturday, they pushed Russian troops back through Vovchansk in the northern region of Kharkiv and may have cleared them out from the southern side of the Vovcha river, which runs through the town. Russian troops mounted a new offensive in Kharkiv on May 11 but have failed to make much headway.

Ukraine’s biggest successes, other than holding the front line, were its deep strikes inside Russian and occupied territory.

On Friday, Ukrainian Army Tactical Missiles (ATACMS) struck the Russian airfield of Saky in Crimea, destroying an ammunition depot and a radar station. On Monday Ukraine struck Saky again and was assessing the damage.

Ukraine first struck Saky in September 2022, forcing Russia to relocate Sukhoi fighter planes stationed there inside Russia. Since then, Saky has been used to launch missile and drone strikes against Ukraine, but Ukraine has struck it repeatedly, degrading its capabilities.

On Saturday, Ukrainian drones struck three Russian military airfields – Engels in the Saratov region, Dyaghilev airfield in Ryazan and Olenya airfield in Murmansk, 1,800km (1,120 miles) from the Ukrainian border.

Ukrainian government sources said the strikes had damaged a number of Tupolev-95 and Tupolev-22 strategic bombers. These included two Tu-22M3 bombers, capable of carrying 24 tonnes of ordnance, which Russia has used repeatedly to drop Kinzhal ballistic missiles on Ukraine. Ukraine also claimed to have damaged Tupolev-134 airliners and an Ilyushin-78 tanker.

On Sunday, as Russian President Vladimir Putin spoke at a naval parade in St Petersburg, Ukrainian drones hit the Polevaya oil depot in Kursk, destroying three of its 11 tanks. On Tuesday, Ukrainian drones destroyed another three tanks at the Vozy oil depot in Kursk.

On Monday, the Ukrainian general staff said its forces had struck four traction power stations in the Kursk, Ponyrovsky and Solntsevsky districts that powered railway lines used to ferry war materiel. Drones also damaged power plants in the Oryol and Belgorod regions.

Ukraine has had success in striking Russian energy and military infrastructure throughout the war and nowhere more so than on the Black Sea.

Ukrainian navy spokesman Dmytro Pletenchuck said on Sunday that aircraft had been completely withdrawn from two of the five airfields used by Russian naval aviation.

The withdrawal of the Black Sea Fleet to Novorossiysk also underscored the success of Ukraine’s naval and aerial drones in containing the Russian navy.