The problem of course is $$$ (€€€)
The EU is going to need to fess up some serious cash to fund their fair share of NATO.
ONE of them...
The other is a whole new re-definition of NATO's mission. And extent of our obligation and involvment given this is going to be 2017. NATO was established back in 1949 when much of Europe was in tatters and broke and threatened by the USSR.
No longer is ANY of the the case, nor has it been for 25 years. The security of Europe is Europe's problem, frankly. That frees up resources that needs to be earmarked for the infrastructure of the USA.