In looking at European-designed fighters of the 4th and 4.5th generation, I keep seeing a common design feature; a box-like structure built into the tail, often in the top half or third. Some examples:
Mirage 2000 (this one's more complex and less box-like but the arrangement is very similar)
Eurofighter Typhoon (this one looks markedly different, much lower and more like an intake)
Panavia Tornado (this one has two main protrusions from the tail, one much like the Typhoon's, the other more like the Gripens or Rafales)
SEPECAT Jaguar (you know what you're looking at by now)
What is this box? My best guess is some sort of avionics/sensor package, maybe RWR/missile warning. What's odd to me is that this box-in-tail arrangement is not seen on any relatively late-model U.S. or Soviet fighter; you'd think if the Europeans were onto something with this placement, the U.S. or Soviets would have tried it out at least once.
I could go on but you get the point, Soviet and U.S fighters seem to have passed on whatever this package is in the tail. So, what is it, why is the arrangement limited to European fighters (for the most part) and how do other regional designers accomplish whatever these do?