They've been going back and forth like this since his first term. Trump and Putin are both routinely lying to one another and getting mad when the other one is caught out. Hell, this backstabbing escalation is what got us into the war to begin with - Trump throwing a bunch of arms into Ukraine that weren't well managed which resulted in a bunch of territory fights. Putin using his own proxies to fuck around on the border, which lead to free-fire in the Donbas between Ukrainian paramilitary and Russia-aligned militia groups. More arms and intelligence fuckery leading to repeated violations of Minsk II, until militias were outright shelling one another from opposite sides of the border.

Biden inherited this shit-show and spent four years trying to put out the fires that Trump's grab-bag of neo-con warmongers and white nationalist Russia-lovers kept spraying lighter fluid all over.

I would not be surprised if this ends with Trump trying to do to Russia what he did in Iran - sending in a flight of B-2 bombers in hopes that they'll magically end the conflict, then trying to claim a victory in the middle of yet another Russian retaliation.