America has, for decades, has been trying to bilk Ukraine into forgoing free Soviet surplus to buy NATO-standardized equipment, only to remotely disable their material while they're using it. Because America was so fickle in providing defense, we've guaranteed that all future peace treaties (eg. one in Ukraine) necessitates direct American intervention, and not vague "security" agreements. That's probably why Trump is brooding over his options right now instead of arranging a ceasefire - he can't get peace without trading away something absurd like US naval assets or direct satellite intel.