Ukrainian authorities put the figure at around 22,800, but the British government have opted for a more conservative estimate of 15,000.
But the only official figure to come out of Moscow is 1,351 deaths.
There has been no updated information from the Russian leadership since March 25, when they added that 3,825 soldiers had been injured in the war in Ukraine.
But fighting a war that is grinding on far longer than the Russian leader may have initially thought, Dr Senior said “Putin is showing clear signs of deterioration”.
The war has made him a “shadow of a man”, which is clear to see through the “overt symbology” the Russian leader deployments.
Dr Senior described the contrast of the image Putin strove to maintain in previous years with the bizarre table he often wedges into meetings.
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Dr Senior continued: “He has metamorphosised from the bear-chested action man riding horses in the Siberian hinterlands to a shadow of a man hiding being comically massive desks.
“Here the overt symbology of power has been hijacked and accentuated for the sake of accentuation almost acting as a physical barrier for protection.”
This table plays a key role in Vladimir Putin’s meetings with global leaders, including a recent meeting with UN Secretary-General, Antonio Guterres.
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But there could be two explanations for the design decision, Dr Patrick Stewart of the University of Arkansas explained to Express.co.uk.
One could a fear of Covid infection, but another could be a more subtle explanation, Professor Stewart suggested.
The length of the table, and therefore the significant space between the leaders, could “be more of an indicator of and emphasis on the distance between the two parties in reaching an agreement”.
The French leader visited the Kremlin for negotiations with Putin over the Russian military buildup on the Ukrainian border, just before Russia launched its invasion.