Reading the article, it didn’t seem all that mysterious. There are apparently a number of “duplex” or “piggyback” shaped charge weapons in existence, which use an initial shaped charge to bore a hole in the target, and then fire a second charge into that hole. I recall reading about preliminary explorations of such technology by the Allies during World War II.
Today the Russians have lead in development in this area. The most detailed info I’ve seen about the various systems was in a GURPS supplement, but regretably I have no better cite at present. The supplement’s bibliography probably does, but I don’t have it handy.
Whatever the specifics of the technology, it seems almost certain to me that the source of it is Russia. That wouldn’t necessarily mean that Putin has some sinister plan afoot to support the Iraqi insurgents, but that either someone in Russia is making a quick buck by doing so, or that lots of this top shelf equipment has been purchased by Iran or Syria, who are in turn supplying the insurgents.
That, in turn, would mean that the insurgency is being supplied much more actively and aggressively than has previously been believed. And if everyone wants to compare Iraq to Vietnam, the Ho Chi Minh Trail may run through Syria… and it may be in for an Arclight strike soon…