Despite that there is no airport in Russian held Ukraine that can operate transport planes big enough to carry them.
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I guess you are limited in your thought process. Without divulging my background, are you aware that many types of field pieces ( and equipment) are easily disassembled in the field into sub assemblies for transport? Been there, done that.
I am quite sure the tube and targeting system was the primary “ assembly” of interest, chassis not so much…..that said, who ever said the captured 19 ton 50 MPH Caesars were air lifted? Ivan moves hundreds of tons of artillery shells a day, ever see the videos of the miles long ammo trains moving ordnance into Ukraine?