Ah, I see. I didn't realise the EU had that agreement.
So I guess the difference is that NATO offers the resources of the US, UK and Canada... and since the US currently (before Germany decided to start spending) spends more than the next 9 countries combined, it's not, ah, nothing. The UK is no slouch in the military spending department either. I honestly didn't realise that NATO had such significant military resources at its disposal.