NASA - Never A Straight Answer .
It could be anything ,.. aliens , secret technology ,.. things that monger more fear then naturally sometimes space rocks fall from the sky . It would worry me more if i knew someone was doing it on purpose .
Did NASA not know or saw it heading for Russia and just didn't care ?
No there are Russians in NASA too. It's 'international' remember. Why would manmade worry you more than natural? Manmade we can do something about, nature always wins and nothing we can do will change it. Plus nature always seeks balance, man just tries to tip it constantly.
Hmmmm ? ,.. what would happen when we warn people about a space rock probably hitting there region tomorrow ? Maybe NASA decided it's best to say nothing and hope for the best . ;-)
You answered your own question ,.. as that's exactly why . No need to worry about nature ,.. worry about the sick wannabe nature controllers that control this realm today .
;-)