Russia invaded Ukraine with 75% of its permanent readiness BTGs as well as conscripts and Rosgvardia troops. They had to stretch the military thin to achieve this, which meant there was never much of a reserve if things went poorly. It isn't about trust, it's about numbers.
Zelensky tells the UN to stop Russia or dissolve itself. "Please show how we can reform or change and work for peace. Or if there is no alternative and no option, then the next option would be dissolve yourself altogether," he says.