Similar taste in language and tea?
I had to go and find the US Embassy statement to check that you hadn't mistranscribed it, but no, they really did write "ensure" rather than "assure" in
"Therefore we want to ensure the good people of the UK that the unthinkable notion of adding salt to Britain's national drink is not official United States policy."
Just goes to show that their skill in language matches their taste in tea-making!