There is a debate underway among nuclear folk over whether Nato's new strategic concept, adopted in Lisbon, is a glass half-full or half-empty from the point of view of disarmament.

Front and centre are up to 200 American B-61 bombs stored in six bases in five European countries. The tactical weapons have long served a symbolic rather than a military purpose in the post-Cold War world, and three of their host nations - Germany, Netherlands and Belgium - have been pushing for their removal as an expression of Barack Obama's self-declared mission to pursue gradual but determined disarmament.

Nobody expected the new strategic concept to sweep them away, but many arms control advocates anticipated that it might at least open the door a crack for their future departure. So did it?

In the "no" corner are the Arms Control Association and the British American Security Information Council (Basic) who have issued a joint statement describing the new doctrine as a "conservative, backward-looking" document and "a missed opportunity".

Two nuclear policy experts have since weighed in, suggesting that the doctrine is not nearly as bad for disarmament as it could have been, and that it does leave room for further steps.

Hans Kristensen at the Federation of American Scientists calls it "one step forward and a half step back", while Martin Butcher at the Nato Monitor, argues that "overall this could have been much less positive".

Who's right? It depends how you parse the language. More importantly, perhaps, it depends what happens in the bigger picture. If the New Start treaty dies in the Senate, it is hard to see where the momentum for reducing Nato and Russian tactical weapons is going to come from any time soon. That may have to await terminal obsolescence over the next decade or so.