President Obama delivers a speech on national security Thursday at the National Defense University at Fort McNair in Washington. Pablo Martinez Monsivais/AP hide caption

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Chinese cyber-espionage is threatening U.S. economic competitiveness. Andy Wong/AP hide caption

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This image from the Federal Bureau of Investigation shows the remains of a pressure cooker that the FBI says was part of one of the bombs that exploded during the Boston Marathon. AP via FBI hide caption

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Venezuela's acting president, Nicolas Maduro, fist-bumps a worker of the state-run oil company, Petroleos de Venezuela, S.A., last month. Maduro faces opposition candidate Henrique Capriles in Sunday's presidential election. Whoever wins will have to tackle the legacy of Chavez's oil programs. Miraflores Presidential Press Office/AP hide caption

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South Korea conducts military exercises near the border with North Korea on Wednesday. Ahn Young-joon/AP hide caption

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