There have been multiple countdowns so far.
Either they are fake decoys and there is only one real one (The booms? How many boom events so far? What happens when the 6th occurs?) occuring "behind the scenes" in a larger timeframe or yet to occur.
Or they are distinct countdowns pertaining to sub-operations. Single arrests, or perhaps the booms? Or just important movement cues?
It's not a warning, it's a threat.