This feels very big: Boris Johnson spoke with German Chancellor Angela Merkel at 8am this morning, and according to a Downing Street source, she told the prime minister that there will be no Brexit deal with the UK unless Northern Ireland is in the customs union "forever".
The source says she repeated "forever" on "multiple occasions".
So what she is saying is there can be no time-limited backstop.
And of course it is a wholesale rejection of Johnson's offer to replace the backstop. "France is saying the same thing", according to the source.
The government's conclusion is that EU leaders have decided to make an example of the UK - to show that Johnson's attempt to bin the painstakingly negotiated Withdrawal Agreement must inevitably lead to a worse deal for the UK.
To be clear, at this stage I only have the UK government's take, but on the face of it the EU has decided to give the UK a binary choice, between a no-deal Brexit or a Brexit delay that may lead to Brexit being cancelled.
Johnson will now go full steam ahead to a no-deal Brexit on October 31. I would expect him to make a statement about all this later today.
It is then down to MPs to decide whether this is the moment to try and oust him with a vote of no confidence, or whether to trust that the so-called Benn Act gets them the Brexit delay they want.
The stakes are very high indeed.