Ukraine is currently under attack by the Russian Federation, which invaded its south and southeast in 2014 and then began a full-scale invasion in 2022. For three years, Ukraine has resisted the largest offensive in contemporary history. The American demands amount to extremely severe war reparations upon Ukraine, far more severe than was demanded (for example) of Germany after either world war. But this demand is directed against Ukraine, and Ukraine is not the aggressor. Russia is the aggressor.
When one country chooses to aid another country, it is understood that this has its basis in the interests of the first country. In any event, one cannot provide aid and then later claim that it is a loan that has to be paid back.
It is morally grotesque, during this war, to put imagined American grievances first.