Okay, so this isn't directly connected to #huntthetruth, but it very well could be, if 343i decides to go this route.
I've been re-reading the Fall of Reach, and on pg 77 we find that Déjà had checked the ONI projections for Outer Colony stability, which dictates when a civil war might begin. We know that these projections are a huge determining factor in Halsey opting to continue with the SPARTAN Program.
I'm curious if Déjà checking the ONI projections was her checking the accuracy of the math based on ONI data, or if it included Déjà actually checking the initial data as well.
If the latter is not true, and if Déjà (and by extension Halsey) used ONI data for their own calculations, then this is where my question/theory comes into play. Could the data that propelled Halsey to agree to carry out the SPARTAN Program actually have been fabricated by ONI, as a means to end those who they did not have control over?
Before you think that ONI isn't capable of such, consider that they've already shown their willingness to go to great (morally unsound) lengths to eradicate those who they feel they don't have complete control over (Kilo Five trilogy). We already know from what's been released of Hunt the Truth that ONI fabricated data, records, and profiles all in attempt to have Benjamin Giraud accept the false history ONI wants told. We can also fairly easily hypothesize from what we know of Master Chief's "betrayal" that ONI has lost control of 117 and seem to be going to great lengths to either again gain control of, or otherwise stop the Chief.
So just from what we've seen and can guess from 343i's tenure, ONI are masters of providing false information for their own agenda, and have major control issues and will even go so far as to commit atrocities and start wars in order to remove uncontrollable entities.
I need to re-read Halsey's Journal (and maybe Ghosts of Onyx, too) and see if I've overlooked something that would directly disprove my theory, but from what I've thusfar seen, I would not in the slightest put it past ONI to fabricate data to such a degree that the "facts" are undeniable to Halsey and she feels she must commit such evils to children (and clones) to prevent an otherwise inescapable war with Insurrectionists.
Edit
If (I realize it could be a very big if) my theory is true, then this could be more of the truth that is either uncovered by Giraud, or possibly has already been uncovered by Halsey (especially if she is in fact FARO). It could also explain ONI's disdain for Halsey, because she is the single greatest threat of making known that ONI lied to get their Spartans in the first place, and once Halsey starts becoming uncontrollable, it greatly scares ONI what could come of that.