I dont know. I dont think they fully know either considering it was taken right under their nose i guess now they are just discovering this. It said that the site were monitored just before the war started and that weapons were stolen after the war had started. How long after, they dont say. I assume this is somewhat recent considering the article was released today. Either that or the sites werent monitored at all and they just found out.
I mean anyway you look at it, this is bad.