The Ukraine situation is a good thing for America. This is the wake up call. As Obama guts the military, we get a vivid example of just how dangerous the world is. Russia can, and will use it's strength to whatever end it feels benefits Russia. America, led by Obama, is retreating and disarming as fast as it possibly can.
If Americans are fine with this, and continue to elect those that further Obama's policies, all is lost. Really.
Oh, and as an aside, America isn't really in a position to do much about Ukraine. But that happened long before the invasion, and you can be sure that was part of the calculus Putin used.