Russian forces continued to pound the Donbas as they sought to encircle the last pocket of Ukrainian resistance in the embattled cities of Lysychansk and Syevyerodonetsk in the Luhansk region while casualties kept mounting on both sides.
Serhiy Hayday, head of the military administration in Luhansk region, where the twin cities are located, said Ukrainian forces are facing massive and relentless artillery attacks in Lysychansk.
"The Russian Army is massively shelling Lysychansk," Hayday wrote on Telegram. "They are just destroying everything there…They destroyed buildings and unfortunately there are casualties."
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Britain's Defense Ministry said in its daily intelligence bulletin early on June 22 that the outcome of the war will likely depend increasingly on the ability of the warring sides to generate and deploy reserve units to the front.
The British intelligence highlighted what it called the "extraordinary" attrition rate among the Moscow-backed separatist forces in the Donetsk region which, based on the figures published by the separatist authorities — more than 2,100 killed and almost 8,900 wounded — is equivalent to around 55 percent of its original force.
The report said separatists appeared to be equipped with outdated Russian weapons and equipment.
It noted that Russian regular forces, which haven't published official casualty figures since March 25, are likely to have suffered similarly high losses.
Ukraine has not published official casualty figures, which it keeps secret, but various officials including President Volodymyr Zelenskiy have suggested as many as 100 Ukrainian soldiers are being killed every day.
On the battlefield, Russian forces captured two towns near the embattled cities of Lysychansk and Syevyerodonetsk in the Luhansk region, Ukraine's military said on June 21.
The captured towns — Pidlisne and Myrna Dolyna — are in the direction of Toshkivka-Pidlisne, the General Staff of the Armed Forces of Ukraine said in its evening report.
The Ukrainian command also said Russian forces have had partial success in the area of Horske and in the direction of Bila Hor, while Ukrainian soldiers successfully repulsed an assault in the direction of Vysokiy.
Ukraine confirmed earlier that Russia had taken the frontline village of Toshkivka.
British intelligence said Russia's offensive, backed by intensive heavy artillery fire, has the primary objective of enveloping the Syevyerodonetsk area from Izyum in the north and Popasna in the south.
Despite mounting casualties, the intelligence bulletin said Russia is "highly likely preparing to attempt to deploy a large number of reserve units to the Donbas."
Zelenskiy said the military situation was very difficult.
"That is really the toughest spot. The occupiers are pressing strongly," Zelenskiy said in an evening video address.
In Syevyerodonetsk, Ukrainian defenders held on to the Azot chemical plant in the city. About 500 civilians are sheltering at the plant, and Hayday said in an interview with the AP that Russian forces are turning the area “into ruins.”
The Ukrainian command also said its forces repulsed a reconnaissance attempt in and around Metyolkine, which Ukraine has confirmed had been captured by the Russians.
The head of the Kharkiv regional state administration, Oleh Synegubov, said at least 15 civilians were killed the region by Russian shelling on June 21.
Six died in and around Kharkiv and another six in Chuhuiv, some 40 kilometers southeast of Kharkiv, Synegubov said. Three died in Zolochiv, 40 kilometers to the northwest of the city.
The command reports Russian shelling of settlements in Kramatorsk, Bakhmut, Avdiyivka, Novopavlovsk, and Zaporizhzhya.