Imagine a parallel Earth that diverges from our own at some point in history close to our current days. The divergence being that, due to interference from a higher power, the nations of the world can no longer wage war against one another.
Let's also suppose that said interference works just perfectly, and now that parallel Earth won't be seeing any wars for the foreseeable future.
Making the song Imagine come true may seem like paradise at first, but this is going to spell doom for many companies that make tanks, fighter jets, destroyer ships and so on.
How would the world economy develop from that point on, if direct, violent conflicts are no longer lucrative?
To make the question narrower, I am interested only on the economical effects. Any social effects, or any other effects of such a cease fire, for this question, are just accessory.