My understanding is that it absolutely is NOT LEGAL in the US. I believe some section of the FAA rules regarding model aircraft states that nothing maybe be "fired" from a model. But rules in Greece may be different.

Still it's very cool and the missiles themselves look very convincing (though perhaps not on a P-51, I don't know).

It is a bit silly though if indeed you can't fire a missile that models B-29s are still allowed to "drop" rocket-powered X1 models.