>aircraft that are malfunctioning?
No, not in this context.
> Birds
Yes, this is milspeak for aircraft. But not malfunctioning ones.
> Fast movers
This term is interesting, because it has a very specific context.
Those who have worked in Space Command, and programs where satellites look down & monitor,
use this term to refer to ballistic missiles and/or near-Earth satellite tracks.
So, it could be a reference to the IRBMs launched from Yemen against KSA.
>Intercepts.