> As a Ukrainian, this sounds like betrayal. We went to war expecting sufficient military support from our superpower partner/ally.
You didn't "go to war". A portion of your sovereign territory was invaded, and you did/are attempting to defend it. The fact that the US/NATO are willing to contribute to your defense is just a plus. Ukraine is not a NATO member and has no defense treaties with anyone in Europe.
> A portion of your sovereign territory was invaded, and you did/are attempting to defend it
Technically true, but if you get some amount of promised military support, you're going to try to be more ambitious in your defense/counter-attack, and you're going to reject unfavourable peace terms.
