Never attribute to malice something that which is adequately explained by stupidity. It's true that US restrains Ukrainians and the war drags on but US does this out of fear of nuclear war with russia. It's silly, but you have to understand that US for many decades built up the marketing myth of russia as a scary superpower. Only in opposition to this great and strong evil they could see themselves as the great and strong good. To facilitate this they told everyone that russia is strong boogyman so much that they themselves believed it and can't shake off this belief even though russia repeatedly displays how weak and terrible at everything it is.