[FairOpinion]

As far as I know, the UN knew about the site, but didn't find some large underground area nearby, which is what the Marines found.

But the news on all that was somewhat fuzzy, and never heard full explanation/clarification.

[John H K]

Also a NYT article today.

As best I can tell, they didn't actually find much of anything the UN didn't know about. That first article seems to have been based on some excitable combat engineers, not the nuclear specialists from this article.

Certainly no "weapons grade plutonium" at all.