[DannyTN]

I also read that the AT&T building was unmarked.

So that likely rules out your average retail customer.

I’m thinking a state intelligence operation.

Would a disgruntled ex-employee be able to obtain that amount of explosives and an RV? And be willing to put that expense into a revenge operation?

[V_TWIN]

Tannerite is readily available. I see it at Acadamy sports in large quantities. Also, there’s this:

https://www.desmoinesregister.com/story/news/crime-and-courts/2020/10/07/iowa-explosion-tannerite-dallas-county-teens-gender-reveal-parties/5908828002/

[WildHighlander57]

https://twitter.com/shanermurph/status/1342553747428421632

[polymuser]

"I also read that the AT&T building was unmarked."

Big city data centers...windowless monoliths. Many of them exist.