The Ukraine crisis does not prove NATO nuclear weapons are useless.
One, if I may point out the obvious, Ukraine is not a member of NATO.
Two, I don't believe that anybody since the early 1950s claimed that the threat of nuclear weapons would deter conventional attack on even a member of NATO. That deterrence required absolute nuclear monopoly on our part to make.
It is simply not credible to believe that nuclear retaliation is a believable threat in the face of a subliminal invasion such as Russia carried out in Crimea.
Nukes deter use of nukes. This allows the fight to remain at the conventional level. Saying that nukes wouldn't deter a Russian conquest of the Baltic states also means that Russian nukes wouldn't deter a NATO counter-attack to liberate them--or to capture Russia's Kaliningrad enclave as a bargaining chip.
Nukes deter conventional advances that threaten a very vital national interest. Their main deterrent value is the uncertainty of what might trigger such a calculation to use nuclear weapons and the general fear that any conflict could escalate to nuclear warfare despite nobody wanting to use nukes.
So I wouldn't say that there isn't some deterrent value against Russian invasion of the Baltic states.
But the notion that because nukes won't deter all forms of aggression they are useless is nonsense. And quoting Russia's Putin to show that leaders don't want nukes any more is kind of laughable given his country's repeated insistence that it doesn't like American missile defenses because it would prefer to be able to threaten Europe with nuclear weapons.
This is why we eventually had to build up our conventional forces in NATO.
The fact that NATO nuclear weapons did not deter Russia from seizing territory from a non-NATO Ukraine does not prove that nuclear weapons in NATO are useless.
Sorry. That story has been hanging around on Real Clear Defense for a while and I finally couldn't resist addressing the nonsense.