Fox three
Indicates launch of an active radar-guided missile (such as the AIM-120 AMRAAM and AIM-54 Phoenix)
from a brevity code used by NATO forces.
My aged grey head dimly recalls an adjunct to SDI involving a missile launch from a high-performance aircraft at very high altitude to intercept incoming ballistic hardware.
...and the specific aircraft I recall in that role was the F-15 Eagle. The very same kinda bird that crashed out around Japanese waters on Sunday(.....?).
Might be a Dead End. Might be a Hot Prospect. I've got critters out in a pasture tangled up in something, so I'll check some more when I get back.