Looking at Q posts that are between pairs of POTUS tweets as being important in some way.

DEFCON could be something along the lines of Define Content or Definite Confirm.

IOW, take the scenario that the first Trump tweet pair (with a trigger delta) is asking about or giving the OK for the next move.

Q posts the stringer describing the action and assigns the delta for the next Tweet pair that will confirm and OK the action.

So, affected parties watching see a trigger Tweet pair, then wait for a Q post that tells them what's next, or, if there is a pre-established time line, to look for a GO command at a certain date and time.

If POTUS second Tweet pair matches delta Q ascribed in his intermediary post than action described is undertaken or confirmed as a GO.

Q then posts confirmation that order was received and go was given.

In addition, perhaps any changes in the Tweet pairs are a 2nd level verification method or a indication of options in the action confirmed that need to be applied.

TL;DR DEFCON is an in-house code word that applies conditions or options on actions to be taken.