As far as I know the constitutions of Germany and Italy forbid to use war and warfare as instrument of settlement of international controversies.I think the US should intervene only by Invitation of which Ukraine essentially set out a distress signal when the Russian invasion commenced with the backing of course from the American people through their representatives.
Only if they are attacked in their territory. Not if it deals with a third country.
They can use other tools like sanctions or diplomacy.
The EU borders with Ukraine.I'd say European countries most certainly has a role to play, being that the invasion is far closer to their Homeland than we are in the states.
Honestly I believe there are Conservatives who are light years away from the interventionist mindset.Personally I view it as being a European problem exclusively , but then again World War II was an exclusive European problem and America didn't intervene until much much later.
As far as I can tell both Europe and North America are proactively involved through logistical support and has remained since the Russian invasion have begun so the justifications revolve around making decisions as to whether Ukraine needs or requires continued support or talking to the Russians to help cease hostilities by discussing concessions.
I can't tell at this point what would actually be better or worse across the proverbial pond.
They analyze, study and then judge.
Like Candace Owens.