a) Big US enterprises are under attack from state-sponsored actors on a daily basis, so it's not that weird. It's not like the NSA weren't caught with their hands in the cookie jar either.
b) If you name the state you think is behind it, you better be ready for the diplomatic repercussions between the US government and the rogue state, as well as potentially stopping doing business in that state (see Google and China)
We can assume that the US government is not the state-sponsored actor in the OP, because their attack has already been publicly known for some time. This one is probably China or Russia.
b) If you name the state you think is behind it, you better be ready for the diplomatic repercussions between the US government and the rogue state, as well as potentially stopping doing business in that state (see Google and China)