Kremlin spokesman Dmitry Peskov highlighted a Ukrainian strike on a Russian military airport in Taganrog on Wednesday as justification, the Russian state news agency TASS reported.
The Defence Ministry in Moscow wrote on Telegram that the Russian response had been to launch a massive attack on Ukraine's fuel and energy infrastructure.
Ukrainian President Volodymyr Zelenskiy called the overnight bombardment "one of the largest attacks on our power grid" since the start of the war in February 2022.
According to the Ukrainian Air Force, Russia's military used 94 missiles and cruise missiles as well as 193 combat drones.
The new commander of Ukraine's ground forces vowed a "massive transformation" of his branch on Friday to improve troop training, management and recruitment.
Ukraine's army says it will strengthen the role of non-commissioned officers as part of a rejig. (AP PHOTO)
The overhaul by Major General Mykhailo Drapatyi, who assumed his post last month, comes as Ukraine's outmanned and outgunned army is struggling to halt a grinding Russian march in the east making its fastest gains since 2022.
The Ukrainian military said the changes would cover training regimes as well as battlefield and logistics management, including by cutting corruption, embracing technology and strengthening the role of non-commissioned officers.
"Today, the ground forces need changes, new energy among its soldiers, and a modern approach to the development of their capabilities," the military quoted Drapatyi as saying at a high-level security meeting.
Ukraine has sought to replenish its ranks through mobilisation and recruitment but has faced difficulties as reports of corruption, poor training and mismanagement have dented enthusiasm for service.
Authorities are also battling a rise in desertions as frontline troops grow physically and mentally exhausted from nearly three years of war.
"Changes will certainly come," Drapatyi said.
"No matter how difficult it is, we have no right not to do it."
Zelenskiy called on Thursday for changes at training centres that would allow recruits to learn directly under battlefield commanders.
He has also appointed a prominent brigade commander as a senior battlefield adviser.
Ukraine is under pressure from outgoing US President Joe Biden's administration to lower the draft age, a move Ukrainian officials have ruled out, saying their forces need more foreign kit to equip the men already mobilised.
Ukraine expanded its mobilisation drive in April, lowering the call-up age to 25 from 27 but since then has steadily lost ground in the east while launching an incursion into Russia's Kursk region.
Ukraine is loath to reduce the mobilisation age further, fearing the damage it could do to the already-bad demographic outlook for the country.
Tens of thousands of soldiers have been killed and millions of people fled the country during the invasion.
with DPA
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