Why would he use an 80 year old tank let a lone one of them in a victory parade?
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Because Moscow and St Petersburg armored regiments are in Ukraine - the only tanks (T-90, T-72) are outside those districts
Not buying it. Using a single 80 year old tank makes no sense and would have been an obvious mistake. The tank could have been used as a symbol for the WWII victory but that would have been clear to anyone watching as a remembrance or something to the fallen tank brigades of WWII.