Well, it looks like Germany is finally showing a willingness to take an active military role on behalf of Ukraine, and if they did, then this just might put a period to Putin's compulsive territorial theft. However, I think that Germany was justified, previously, in being hesitant to help Ukraine when it was unclear whether or not the Ukrainian people would be determined to take an active role in their own self-defense. However, it looks like the Ukrainian people are preparing to make a serious go of fighting back against a Russian invasion, so I think it is appropriate that Germany would join them now as an ally. Decisive military action to forcibly rebuff Russia would probably cost less lives than letting Russia get themselves into a prolonged military quagmire, with Ukrainians fighting to throw off such an occupation.
If it does come to blows, in Ukraine, then I think that the US would be justified in joining on the side of NATO forces, assuming that western Europe had a genuine commitment.
It is also extremely rare for me to side with a hawkish policy. It looks to me like Russia is in a process of territorial expansion. They took Crimea because they were hopeful of establishing naval supremacy in the Black Sea. I don't think they have any intention of being satisfied under any circumstances whatsoever. If they were allowed to take Ukraine, then they would go for Lithuania, pulling the same trick of repeatedly putting their thumb on the scale and undermining the country's political stability until the point where they rolled over like a dog. They are already making war. They have already invaded and occupied parts of Ukraine. They have already invaded and occupied parts of the Republic of Georgia. They have succeeded at subverting Belarusian resistance against them, making Belarus effectively a satrap and independent in name only. and they have made threatening gestures toward Lithuania. They are already at war, and I think it's a little bit unhinged to pretend otherwise.
The only question is at which point the US ought to intervene. I would need evidence that the rest of Europe is going to get serious about their own self-defense. I am not really comfortable with the idea of Europe's defense strategy leaning too heavily upon their relationship with the United States. It already causes serious strain, in our international relations, that we have as strong of a role in that relationship as we do. It is hard for the United States to do business with China and other countries because they see us as dangerously imperialistic, and this is not entirely without justification. The more that Europe (meaning current and prospective NATO participants in Europe) shows a willingness to play a leadership role in resisting Russian expansion, the more inclined I am to side with my country lending them support.