In regards to our defense budget, anything is economically beneficial. If a country, continent, or any entity notices a weakness in our national defense systems, they will exploit, and in turn take us out. Which will in turn create more turmoil than anybody wants. As far as economy, compared to what we would lose as a nation, I believe it is definitely necessary.
I do no think that the European missile defense would be economically beneficial at all. I do not think that any missile defense would be economically beneficial. I think that we need to stray away from missile defense or any kind of warfare and focus on what is really important, the environment.