The Strategic Concept paragraph n missile defence reads:
We will ensure that NATO has the full range of capabilities necessary to deter and defend against any threat to the safety and security of our populations. Therefore, we will:
• develop the capability to defend our populations and territories against ballistic missile attack as a core element of our collective defence, which contributes to the indivisible security of the Alliance. We will actively seek cooperation on missile defence with Russia and other Euro-Atlantic partners;
There are a number of useful stories on this here, here and here.
There are dissenting voices. US conservatives oppose spreading the BMD decision to include Russia, something that the Obama administration has made a central part of the reset of relations with NATO’s former enemy. They claim that Russian participation will render any system ineffective. (See this for example)However, since US conservatives are inveterately and irrationally hostile to Russia, and also backed enormous spending on missile defence systems that demonstrably do not work, probably cannot work and even if they did could be easily tricked by countermeasures, we probably shouldn’t take their views to seriously.
More serious for NATO was the Turkish objection, based on regional sensitivities, notably refusing to name Iran as a potential enemy which made the missile shield necessary.
Any such stance was dropped from official documents and the missile shield (effective or not) will go ahead.
Over dinner, Alliance leaders decided to invite Russia to participate. The cost of the proposed system is said to be some $270m over the next ten years, which ensures it will be extremely limited. The US spends far more each year to very little effect. Of course, NATO Summits have been agreeing to work on missile defences since the early 1990s, with few results. Let's see where this one takes us.