We're in crazy-town because of Trump and the Republicans, with very real consequences.
But the collapse of the EU/US relationship means you probably want to plan for the potential of a similar collapse within the European alliances.
IIRC the UK has committed its nuclear weapons to defend NATO countries.
So has the US, which is part of why this is so odd of an approach. Technically we’re required to nuke ourselves if we attack Greenland.
They largely rejoined in 2009 (and very deliberately never rejoined NATO's Nuclear Planning Group), but if any NATO member is capable of going it alone on this one, it's probably France.
240 nukes on subs is plenty to wave around as a stick, too.
Even if American defences stopped 80% of them, estimates say France has enough (290*(1-0.8)=58) to destroy every state capital.
Is more really necessary, if the goal is simply to deter?