As a follow-up, thoughts from someone I know who had rather high level security clearance for over a decade (via the Senate foreign intelligence committee):
Key points, not just coming from us lay people, but from someone who was occasionally in the room as strikes were being discussed, prepared, and launched:
1) using non gov't apps and devices to communicate official info is intended to avoid accountability and the legal requirements of maintaining records of gov't action.
2) everyone knows that this is an unacceptable security risk.
3) failures like this actually put the lives of our "warfighters" (man, the conservatives love that word, so let's use it) at risk. If news of planned targets and delivery platforms (F-18s) were leaked in advance, the enemy would have had the opportunity to put AA resources along the way, possibly shooting down and killing some of our aircrews.
It was done for an illegal and criminal purpose, and created risk not just in theory, but to actual lives of American servicemembers, all because we are staffed with criminal rank amateurs. Fucking well-done, Trump administration. I'd call your entire admin a shitshow, but that would be an insult to turds that actually perform the function of evacuating waste from the human body.