Their conclusion is based on estimates of centrifuge processing in Iran not on any actual missile building. It also is much more precise than previous estimates which estimated the possibility of Iran nukes years in the future.
So why the sudden revision in estimates? Iran centrifuges were hit and presumably disabled by the Stuxnet virus so that should have slowed things down. Yet now we have unmistakable drum beats for military action against Iran based on a a very near-future estimate that Iran could (not can or will) produce nukes.
In order to halt the process, Jones comments, forces will have to deploy ground forces – airstrikes will no longer be sufficient.
Good luck with that. Iran has a loathsome government but troops on the ground there would be beyond insane.