A line has been drawn in the sand over arms sales to Saudi Arabia.
It's been drawn after the weekend bombing of a funeral hall in Sanaa.
The Foreign Office position has hardened.
One source told me today that the Saudis need to hold a full investigation, they need to hold it soon and it needs to be credible, not a whitewash.
Previously when I've spoken to the FCO about this the position has been that the Saudis are our allies and we trust them to investigate their own mistakes. Not any longer it seems.
And the UK should be in a position to form a judgement.
I understand there are around half a dozen British Military Liaison Officers based in the Saudi Operations Centre.
These officers are not involved in targeting but they do feed back information on what the Saudis are doing.
If the investigation is not judged to be credible then the UK will review its arms sales to Saudi.
Those opposed to UK arms sales already know what they think about the Saudi investigation.
"Saudi Arabia has a total contempt for Human Rights so can't be trusted to investigate itself." says Andrew Smith of the Campaign Against the Arms Trade.
The question is, if the Saudi's fall short on this will these lucrative arms sales seriously be reviewed? And potentially halted? Or will the Government just draw a new line in the sand?