This week's stunning story about Washington's group chat mix-up has prompted a White House campaign against the looped-in magazine editor and a debate over what constitutes "war plans".
"Nobody was texting war plans," US Defense Secretary Pete Hegseth has repeatedly said since The Atlantic's revelations; comments echoed across the administration.
The Atlantic has now published screenshots of the chat thread and invited readers to judge for themselves.
Here's what we've learned and what's happened since.
The 'war plans' are revealed
Jeffrey Goldberg's initial report described the "war plans" in the chat as "precise information about weapons packages, targets, and timing".
The key message about those plans, posted to the chat by Mr Hegseth, began by stating the weather was favourable.
TEAM UPDATE:
TIME NOW (1144et): Weather is FAVORABLE. Just CONFIRMED w/CENTCOM we are a GO for mission launch.
1215et: F-18s LAUNCH (1st strike package)
1345: "Trigger Based" F-18 1st Strike Window Starts (Target Terrorist is @ his Known Location so SHOULD BE ON TIME) — also, Strike Drones Launch (MQ-9s)
1410: More F-18s LAUNCH (2nd strike package)
1415: Strike Drones on Target (THIS IS WHEN THE FIRST BOMBS WILL DEFINITELY DROP, pending earlier "Trigger Based" targets)
1536: F-18 2nd Strike Starts — also, first sea-based Tomahawks launched.
It then outlined a sequence of events, including when F-18 fighter jets, strike drones and Tomahawk cruise missiles would launch, with precise information about the timing.
It did not include precise information about targets. But subsequent messages, posted after the strikes, referred to the Houthis' "top missile guy" and his "girlfriend's building" being hit.
National Security Adviser Mike Waltz wrote:
VP. building collapsed. Had multiple positive ID. Pete, Kurilla, the IC, amazing job.
Vice-President JD Vance responded: "What?"
Mr Waltz then wrote:
Typing too fast. The first target — their top missile guy — we had positive ID of him walking into his girlfriend's building and it's now collapsed.
After a string of congratulatory messages, and several emojis from Mr Waltz, Mr Hegseth wrote:
CENTCOM was/is on point. Great job all. More strikes ongoing for hours tonight, and will provide full initial report tomorrow. But on time, on target, and good readouts so far.
The Atlantic published the chat thread under a headline that referred to them as "attack plans". The White House said that meant the magazine was admitting they weren't war plans.
Defence experts say there are important differences — war plans outline an overall strategy for a conflict, whereas attack plans focus on a specific operation. But both would generally be classified.
"One could actually make the argument that attack plans are more sensitive because they are more detailed and specific on time, place and manner," former CIA official Mick Mulroy told The Wall Street Journal.
Was it classified information?
The Trump administration continues to insist the Signal exchange did not include classified information.
But some have pointed to the Department of Defense (DoD) manual, which says material should be classified if:
"… the unauthorised disclosure of the information [could] reasonably be expected to cause [serious] damage to the national security", including "military plans, weapon systems, or operations".
A 2009 executive order, still in place, uses similar language.
Democratic congressman Raja Krishnamoorthi read from both documents at a hearing of Congress's House Intelligence Committee and said:
"Applying the executive order as well as the DoD manual to this fact pattern, we clearly have weapon systems that have been identified. That is classified information."
The Trump administration, though, says the classified details were confined to an authorised communications channel referred to as "high side". In one of the Signal messages, Mr Waltz told the group:
Team, you should have a statement of conclusions with taskings per the president's guidance this morning in your high side inboxes.
Many Republicans are toeing the White House's line.
But one Republican member of Congress has publicly broken ranks.
Don Bacon, a retired US Air Force brigadier general and intelligence specialist, told The Hill:
"The WH is in denial that this was not classified or sensitive data. They should just own up to it and preserve credibility."
Democrats' calls for heads to roll have only intensified.
Senator Tammy Duckworth, a former Blackhawk helicopter pilot who served in Iraq, posted online:
"Pete Hegseth is a f***ing liar. This is so clearly classified info he recklessly leaked that could've gotten our pilots killed. He needs to resign in disgrace immediately."
Secretary of State Marco Rubio said "someone made a big mistake" but the Pentagon had told him the information wasn't classified.
Larry Pfeiffer, a former CIA chief of staff and White House Situation Room senior director, told the ABC:
"I've never seen the kind of information that Mr Goldberg showed us today as not being classified … It is really ludicrous to claim that it is not classified."
Waltz takes responsibility and recruits Musk
Earlier, Mr Waltz, who set up the chat, said he took responsibility for the journalist's invitation to join.
"I built the group," he said.
He still says he has no idea how he added Goldberg. He told Fox News:
"I just talked to Elon [Musk] on the way here. We've got the best technical minds looking at how this happened.
"But I can tell you for 100 per cent, I don't know this guy.
"I know him by his horrible reputation — and he really is the bottom scum of journalists — and I know him in the sense that he hates the president, but I don't text him. He wasn't in my phone."
[tweet]Trump suggests the app's to blame
On Wednesday evening, local time, President Donald Trump was asked if Mr Hegseth should consider his position.
Mr Trump then suggested the Signal app itself could have been the problem.
"How do you bring Hegseth into it? He had nothing to do it," he said.
"It's all a witch-hunt.
"… I don't know that Signal works. I think Signal could be defective, to be honest with you, and I think that's what we have to — because you use Signal, and we use Signal, and everybody uses Signal, but it could be a defective platform. And we're going to have to find that out."
Memories are refreshed
Two of the officials involved in the chat — Director of National Intelligence Tulsi Gabbard and CIA director John Ratcliffe — have been questioned by a Senate committee for a second day.
On Tuesday, Ms Gabbard said she could not recall discussions of weapons, timing or targets taking place in the group chat.
Pressed on whether that was true on Wednesday, she told the Senate Intelligence Committee she stood by her response:
"Obviously the release of the screenshots that came from that chat group today were a refresher on what happened. As I said earlier, I was not involved with that portion of the chat, so it did not come to my recollection yesterday."
