I believe there is a little leeway. If your music is ME inspired or ME fusion in many cases no problems. But if you are using belly dance movement vocabulary to non-ME music I would consider the result belly dance fusion at best - and that only if the resulting performance still has the feel of the solo, improvised dance styles from the Middle East.
The movement vocab only with non-ME music can be a number of styles. What I see most often is jazz or theatre dance.