That Britain's national interest is best served in a flexible, adaptable and open European Union and that such a European Union is best with Britain in it.

BBC: David Cameron speech: UK and the EU

"To be adaptable and flexible is a path to survival, " said Shambaugh.

CNN: A conversation with China's young Communists

And he set out a vision for an "updated" European Union that is "more flexible, more adaptable, more open, fit for the challenges of the modern age" -- and said all options should be on the table to negotiate a new deal.

CNN: Cameron promises referendum on Britain's place in Europe