The US President flew into an active peer vs peer war zone. What if the Russians took a shot at him? How would we respond?

 Biden flew into an active peer vs peer war zone.

The Russians were warned that he was heading there, but I have to wonder. What if they took a shot at him?

What if they put together a MASSIVE AIR STRIKE?  What if they legitimately claimed that they were targeting Zelensky and not the US President.

Would we declare war over an attempt (even if successful) at the killing of a US President that went to a war zone?

Would we even posture about it?

Then the next question becomes WHY DIDN'T RUSSIA TAKE A SHOT A BIDEN!!!!

This was a golden opportunity to put the NATO on its back foot and extract a bit of revenge on their main protagonist.  WHY NOT GO FULL TILT BOOGIE AND ROLL THE DICE?

We all assume that everyone involved is fighting to win.  I sometimes wonder.