Was it? On the face of it it looks that way, but it may be misleading.
And if it was a truck, whose was the truck, what was it carrying, how did they get it past security (alleged to be stringent), who was driving it, and how was it set off.
If Ukrainian covert operatives could pull this off they could do a lot else as well.
Perspective from Zelinsky’s top advisor Podolyak:
Now seriously. FSB/PMC try to eliminate leadership of Defense Ministry/GHQ. Before personnel change, FSB is in knockdown — missed Putin’s bridge explosion. Defense Ministry can now blame FSB for the future South loss. Isn’t it obvious who made an explosion? Truck arrived from RF.
https://twitter.com/Podolyak_M/status/1578714525867859969
The Ukes did it the same way as they murdered Dugins daughter. Truck with explosives. Unwitting driver. Car at a distance remote detonated it.