I once made a French diplomat really angry by suggesting that the persistence of the modest-sized British and French nuclear arsenals sent a really bad message about nuclear proliferation to regional powers all around the world. This interesting WikiLeaked cable from London about British thinking on the Trident and the French reaction to it offers some evidence in this regard.
Charli Carpenter explains:
The French reaction is very interesting indeed; the French appear to have understood a decision to reduce or eliminate the UK’s nuclear force as a danger to France’s own nuclear capabilities. Presumably, the threat would come from activists and political actors within France, who would leverage British de-nuclearization in arguments against the maintenance of France’s own deterrent.
This suggests that France and the UK, even prior to their recent defense agreement, understood their nuclear deterrents to be symbiotic rather than competitive, even in a symbolic sense. The British and French nuclear arsenals have never threatened each other in anything other than a symbolic sense; the sole possession of nuclear weapons could conceivably suggest military and political leadership of Europe. I had long believed that the persistence of the French nuclear arsenal was the most important reason that Britain would not de-nuclearize, but I had assumed that this was because giving up Britain’s nukes might be perceived as a concession of French military and political predominance. What I didn’t expect was that the French would put direct (if discreet) diplomatic pressure on the United Kingdom out of fear that they might lose the rationale for their own arsenal.
This suggests that British nuclear disarmament might indeed send a powerful diplomatic message. Of course, France and the UK are the most similar of the nuclear powers, and it would be a reach to suggest that India, China, etc. would feel the same pressure to disarm as France. Nevertheless, that the French take the symbolic power of the message so seriously is very interesting indeed.
I would say that the issue here isn’t so much the Indias and Chinas of the world as the Brazils and South Africas. Whether public opinion in non-nuclear third world democracies is more inclined to believe “responsible liberal democracies are moving toward disarmament” or else “important countries each need an independent nuclear deterrent” is relevant to the long-run trajectory of policies in these countries. And the posture of the British and French governments is a big boost to option number two, in a way that’s bad for the world.