I understand why the US says this, but I really hope it's strategic rhethoric under the hopeful presumption that they'll never have to actually follow through. As much as I appreciate the US as our security guarantor, I really would rather not have the warfare spread out of Ukraine, which I think would be a given if the US gets involved in a tit for tat game with Russia. I realize it sounds very cynical saying it, but I don't think most European voters (except Poland and Lithuania maybe) are willing to risk this kind of escalation on the European continent, even with the kind of support we see for Ukraine now.