Hope it works out. My fear is that Trump wants a deal more than Putin does. Trump is also unfamiliar with the facts. These negotiations require detailed knowledge of the ground, Trump will never care to know. Hence, he can be manipulated.
But, it there is a deal, Putin has to know that if Russia thereafter breaches the deal afterwards, the breach will be considered an act of aggression against the United States.
And Trump needs to embrace that line in the sand more than Putin.