BOOTHBY: Humans. You've got a flair for the dramatic, I'll give you that. You want to keep talking? Fine by me, but no more beating around the bush. Now what do you want from us. The truth, Captain.
JANEWAY: Voyager is alone in the Delta Quadrant. We haven't been in contact with Earth for over four years.
BOOTHBY: Explain why you attacked our realm, hand in hand with the Borg.
JANEWAY: At the time, we didn't realise the Borg had started the war against you. We forged a temporary alliance with them because we thought you were the threat.
SEVEN: Your galaxy will be purged. Sound familiar?
BULLOCK: We were only trying to defend ourselves.
TUVOK: If that's true, why are you still in our galaxy? Your conflict with the Borg ended over a year ago.
As far as 8472 was concerned in In the Flesh, their "warcry" was more of a threat than a promise... Even though it was originally released as a threat and a promise.
I mean, when Worf says things like "death tot he opposition" during baseball games, do we really expect him to follow through on that chatter?