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It is a great pleasure to be back here at the Heritage Foundation. The Foundation was kind enough to provide a platform in the United States to me and the British Conservative Party during our years in opposition. I said then I would return to speak to you as the U.K. Defense Secretary. I am pleased to shock you by fulfilling a political promise immediately.

Together, the United Kingdom, the United States, and our allies around the world face a difficult security environment, where the outlook is sobering and the threats diverse, growing, and unpredictable.

We live in a period in which our countries face few direct military threats, but in this globalized environment, the scourge of terrorism, the danger of nuclear proliferation, the ungoverned space that characterizes...