While some folks have expressed fear, anger and dismay towards the new nuclear policy (or at least their straw man versions), I am not worried.
While the policy does mark what appears to be a significant change, it actually appears to have little practical impact on how we would actually wage war.
The policy is that we will not use nuclear weapons on non-nuclear countries. Unless, of course, they are in violation of the Nuclear Non-Proliferation Treaty (that means, for example, we can still nuke Iran) or they use biological weapons against us. This is, of course, the approach taken by the United States in the post WWII world. After all, we did not use nuclear weapons in Korea, Vietnam, Afghanistan or Iraq. Even more importantly, all the major potential threats to the United States (Russia, China, North Korea, and Iran) are still legitimate targets for nuclear weapons. The countries that are excluded by this policy are hardly major threats to the United States.
Obviously, this policy does not actually change the nuclear weapons so that they can only be used in such situations. Should the United States face a truly dire situation that could only be resolved by nuclear weapons being employed in a way that violates this policy, then the weapons would certainly be used. While Obama is cast as a weakling socialist, he would not allow the United States to be destroyed just so he could stick with this policy.
Of course, it might be argued that this is a meaningful political change. After all, it seems to have outraged many folks on the right. While much of their alleged outrage is probably mere political posturing, they certainly do seem to think that it is worth attacking. While this does not prove that this is really a meaningful policy change, it does suggest that this might be the case.
Also, it does seem to reflect a change in language and creates the appearance that we are further leashing our nuclear beast. And, as is often said, appearance is (seen as) reality in politics.
As I see it, the change is primarily rhetorical. This is, I think, a smart move. Obama can use the policy to improve how America is seen by the world and score political points without actually reducing America’s security. However, he does run the risk that the Republicans will also use this to score political points, even if they have to attack a straw man version of the policy.