Twaddle!
This bit:
"The decision to publicly attribute this incident sends a clear message that the UK and its allies will not tolerate malicious cyber activity, the Foreign Office said."
Bollocks.
You are making this announcement because you *know* Trump is going to blab it. Full stop. End of story.
You've realised you'll look daft if you simply nod and agree with him after the fact, and even worse if you get into a public spat over Yes it was/No it wasn't.
Biting the hand that feeds IT
