Of course they do - the Germans conquered Ukraine twice in the last 100 years. Ukraine was part of the Russian Empire for hundreds of years. As sympathetic as I am for the Ukrainians, it's hard to see this being the business of the European Union, let alone the United States. Russian reluctance to have NATO troops at its doorstep is hardly irrational.
Let the Ukrainians do something. So far they are making the ARVN look competent in comparison.