Zelensky needs to host them both in Ukraine along with Vance and Johnson, end them, and then just act like nothing happened. Just say they never arrived, or were going to go have drinks together after the talks and no one heard from them since.
Seriously, what the fuck is Russia going to do? Go to war with you? Lol. As for the US, you just solved our biggest immediate problems, and you'll get your aid back once emergency elections are over