He has a PhD from Yale in diplomatic and military history.

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"There was a feeling in Canada that it had to be done, " said Alan Henrikson, a professor of diplomatic history at Tufts University.

CNN: In Canada, Afghanistan not 'forgotten'

While there is time and space, we believe, for the diplomatic course to be pursued in conjunction with increasingly stringent sanctions that are already the most stringent ever in history, we know, too, that there is not unlimited time.

WHITEHOUSE: Press Gaggle aboard the Press Bus en route Davenport, IA