What Does the Brexit Mean for NATO & European Security More Generally?

At NATO's most recent Summit the Heads of State and Government were surprisingly silent on discussing the impact of Britain leaving the EU for NATO. However, the Brexi vote is a critical moment for the alliance as it started to re-adjust its relationship with the European Union and European security more generally. The question that remains is what impact does the Brexit leave have for the project of European integration and specifically the transatlantic relationship? Can we expect, for example, an increased UK investment to NATO now that it pulls its EU commitmnets (roughly 13 billion pounds)? And if so, why? And what does this mean for the 'special relationship' that the UK apparently had with the United States?