IIRC the UK and France have enough nuclear weapons to decimate an industrialized economy. The UK also shares some of its nuclear weapons program with the United States through the servicing of its Vanguard class submarines at King's Bay, GA.

They do not have enough to create an exchange that could wipe out human society, which is the deterrent that the US brought to bear.

If you are Vladimir Putin, with enough infrastructure to possibly protect yourself and your ruling class from an attack of 120 warheads, but not 1700, your calculus for the use of nuclear weapons - particularly the tactical type, of which Russia has many - changes considerably if the people with 1700 warheads are no longer going to use them against you.