"Promises were broken and trust is lost," said Isak, who wants to join Liverpool before the transfer window closes on September 1. The Swedish internationalist's position is that he has long since made his desire to leave St James' Park clear to Newcastle's hierarchy, and that those in charge had vowed to honour that.
"No commitment has ever been made that Alex can leave this summer," the club replied.
Who promised what to who, and when, can be speculated upon and debated no end, but it's probably a little irrelevant now. By going public, and in such emotive terms, Isak has essentially gone nuclear in an attempt to get what he wants. And that, whether they care to admit it or not, is a problem for Newcastle.
The last line of their response to him was to emphasise that he remains part of the 'family' and kept the door open for him re-joining Eddie Howe's squad at some point. And while their stance remains that Isak is 'not for sale', they do have to leave that door ajar in the hope his stance will soften after the transfer window closes and no move materialises.
Newcastle might be just gambling on the possibility that if they refuse to sell Isak, he will conclude that he's better off trying to reintegrate for the time being, as opposed to putting his career on hold with a World Cup on the horizon next summer.
The trouble there, though, is that this whole drama isn't just going to disappear come September. The Newcastle supporters certainly will not move on so readily.
They have made their feelings abundantly clear that this a betrayal on Isak's part. It wasn't so long ago that he was scoring the winner as Newcastle ended a 56-year wait for a major trophy, against Liverpool of all clubs, in last season's Carabao Cup final.
He was honoured with a huge display at St James' Park, the forward proclaimed as 'Alexander the Great'. How quickly that can all go away in football.
The pain of rejection stings like few others, though, and that's what this is for Newcastle fans. Under Saudi-Arabian ownership, they hold ambitions to establish themselves among the world's elite, but that their best player will go to such lengths to force his way to a domestic rival is a bitter reminder that they are not there yet.
Internally, Newcastle may feel they can coax Isak back into the fold, but will their supporters ever accept him again? Especially when they will know the same situation will arise again in January?
There is truth in the old cliche: never keep an unhappy player.
To sell Isak now might look like a capitulation on a strongly-held stance, but perception will be the least of Newcastle's worries when there are much more tangible dilemmas to wrestle with. Having their £150m valuation met is a decent way to save face.
Their biggest issue would be in adequately replacing him within a very small timeframe. An influential subplot around the Isak saga is that Newcastle have struggled to sign another striker this summer.
They have been linked with Liam Delap, Joao Pedro, Bryan Mbeumo, Benjamin Sesko, Yoane Wissa and Hugo Ekitike, who have all either stayed put or gone elsewhere. The latter, of course, was taken from under their nose by Liverpool. Newcastle could not justify selling Isak to their fanbase if they cannot sign a successor, as would be with the case with any important player.
Even if Isak is not sold and a return to Howe's squad is negotiated and formalised, he has not trained with his team-mates all summer, never mind clocking up any minutes on the pitch. One way or another, he won't be starting games for Newcastle any time soon.
Howe has tried his best to remain diplomatic, but it's he who is caught in the middle of all this. His job is to field as strong a team as possible, and he will know that team would be infinitely better with Isak in it, so he cannot burn his bridges with the 25-year-old while he's still under contract.
But no manager wants this kind of circus hanging over their day-to-day. Every time Howe steps in front of the media, this is the topic that will be front and centre, even though it's reached a stage at which there is very little else he can say.
Watching on with intent, of course, will be Liverpool.
The Premier League champions have already had a £110m bid for Isak rejected out of hand, but speculation is rife that they will return to the table before the deadline. They are in a pretty comfortable position, it must be said.
Even without Isak, they have been tipped as favourites to retain their league crown, and have already enjoyed a prolific summer transfer window. So enthused are their supporters by the summer's recruitment, Isak is being viewed somewhat as a possible bonus. Not essential to their plans, yet potentially seismic all the same.
Isak might yet get his way in the end, but he hasn't exactly covered himself in glory. Football is a brutal, ruthless business, we all know that. But there are ways in which to conduct yourself, and it's difficult to choose the route Isak has without coming across poorly. He was idolised on Tyneside, and it's always a little disheartening when a player appears to show little reverence for that.
That being said, we are not privy to the truth behind the claims and counter-claims between Isak and Newcastle. As is often the case, there are likely to be elements of this that could have been handled better on all sides.
But as the end of the transfer window approaches, perhaps Howe said it best this week - that Newcastle have very much found themselves in a 'lose-lose' situation with this.