Gun-missile?

Time to sic my crack research squad (that's you) on a vexing question. What the hell is this thing?

It doesn't appear to be a APFSDS (armor-peircing, fin-stabilized, discarding sabot) round, since it's the diameter of the gun bore that fired it. Note also that it is quite clearly of a long-axis folding fin design, similar to 2.75" aerial rockets, and appears to have an opening for a rocket motor in the back of it. Additionally, it triggers off what I can only guess are some sort of stabilization or guidance charges in mid-flight.

I didn't think anyone was producing tank gun-fired missiles since the Shillelagh was retired. The BMP-3 has a gun/missile launcher, but the barrel in the video is quite clearly that of a MBT.

I can't place the tank, though; the apparently offset bore evacuator suggests a Western tank, but the clean lines of the barrel suggest an early (pre T-72) Soviet tank. The evacuator is too far forward to be a Chinese T59, the only Soviet-derived offset evacuator design that immediately springs to mind. I suppose it could be one of the international variants of the Leopard series.

But that still doesn't tell me what the missile is... Most vexing.