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

itoggle caption AP via FBI

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

itoggle caption Miraflores Presidential Press Office/AP

South Korean marines work on their K-55 self-propelled howitzers during an exercise against possible attacks by North Korea near the border village of Panmunjom in Paju, South Korea, Wednesday. Ahn Young-joon/AP hide caption

itoggle caption Ahn Young-joon/AP

Director of National Intelligence James Clapper says the danger of a devastating cyberattack is the No. 1 threat facing the U.S. He made the assessment Tuesday on Capitol Hill before the Senate Intelligence Committee hearing on worldwide threats. Susan Walsh/AP hide caption

itoggle caption Susan Walsh/AP