There is no question in my mind that a 'Brexit' would deal a significant blow to the E.U.'s strength and resilience at exactly the moment when the West is under attack from multiple directions.

Obviously, resilience matters. I was no stranger to adversity, but it's different when it's personal. Not something I would recommend.

Now we're going to find out the resilience of this White House. There's no question this is the single most difficult moment in public opinion that this White House has faced in office.

In the 101st Airborne Division headquarters in Mosul, we had a sign on the wall. It was a question that we would ask ourselves before every new operation or policy initiative. It asked: Will this policy or operation take more bad guys off the streets than it creates by its conduct?

This is a very significant deal.

The oak fought the wind and was broken, the willow bent when it must and survived.