“We need to make clear that if he targets our good friends the Brits, we will bring civilization to an end in the Northern hemisphere.”
We’re in the process of doing that anyway, with our Ukraine adventure. So why bother trying to threaten Russia over the UK?
And a most excellent adventure it is turning out to be, save a lot of folks who have given up their lives for nothing much, and wrecked Ukraine. Still you need to break eggs to make an omelet. And if you think that is trite, it is no more trite than Blinken's view of foreign policy.