Vladimir Putin's army has adopted a style of warfare abandoned by most modern militaries, the British Ministry of Defence said on Friday.
The Russians have used huge amounts of energy and resources constructing "extensive defensive positions" and digging trenches along the front lines in Ukraine.
Russia's military planning has remained "largely unchanged since the Second World War", the MoD said.
In it's morning briefing, it added: "As shown by imagery, in recent weeks, Russian forces have continued to expend considerable effort to construct extensive defensive positions along the front line.
"They have likely prioritised the northern sector around the town of Svatove.
"The Russian constructions follow traditional military plans for entrenchment, largely unchanged since the Second World War. Such constructions are likely to be vulnerable to modern, precision indirect strikes.
"The construction of major defensive lines is further illustration of Russia’s reversion to positional warfare that has been largely abandoned by most modern Western militaries in recent decades."
It comes as Russia launched another round of mass air strikes across Ukraine on Friday.
For the second time in days, a barrage of rockets were fired at several regions across the country in an apparent bid to further destroy Ukraine’s power grid.
Explosions were heard in the capital, the south western district of Holosiivsky, on Ukraine’s right bank, as well as the eastern districts of Dniprovskyi and Desnyanskyi, according to Kyiv’s mayor Vitali Klitschko.
It is not yet clear if any Russian rockets hit their targets.
Kyiv has warned that Moscow is planning a further deadly extensive ground offensive early in the new year, despite recent Russian military setbacks.
Ukrainian President Volodymyr Zelensky and senior officials accused Russia of plotting to attempt more devastating strikes in early 2023.
Moscow's ability to conduct successful offensive ground operations is rapidly diminishing after a series of battlefield losses and an anti-war sentiment reportedly sweeping through Russia.
Ukraine's Defence Minister Oleksii Reznikov said evidence was mounting that Russia plans a broad new offensive in February when half of Putin's 300,000 newly conscripted troops complete training.
