North Korean leader Kim Jong Un waves during a parade in Pyongyang, North Korea, in October. The country said it carried a successful hydrogen bomb text on Wednesday morning, but many analysts are skeptical. Wong Maye-E/AP hide caption

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Chinese Foreign Minister Wang Yi delivers a speech during the international seminar commemorating the 10th anniversary of the September 19 joint statement of six-party talks at the Diaoyutai State Guesthouse in Beijing, China, on Saturday. Kim Kyung-hoon/Reuters/Landov hide caption

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President Obama listens to Israeli Prime Minister Benjamin Netanyahu during their March 22, 2013, visit to a Holocaust memorial in Jerusalem. Pablo Martinez Monsivais/AP hide caption

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North Korean leader Kim Jong Un, seen here in an undated picture released by the Rodong Sinmun newspaper, has said his country will never give up its nuclear weapons. In the photo, Kim was visiting a hydroelectric power plant. Rodong Sinmun/EPA /LANDOV hide caption

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An Iranian security guard at the Bushehr nuclear power plant in 2010. Iran and negotiators from six world powers are trying to work out a long-term deal on Iran's nuclear program. Vahid Salemi/AP hide caption

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The Stickiest Issues In The Iranian Nuclear Talks
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A Minuteman III intercontinental ballistic missile can hit almost any target on earth ... but only if it flies through Russian airspace. This unarmed test version was launched from Vandenberg Air Force Base in California. V.A. Mouzon/Tech Sgt. Vincent Mouzon/U.S. Air Force hide caption

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Should America Keep Its Aging Nuclear Missiles?
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A worker walks inside the turbine hall of the Sizewell nuclear plant in eastern England in 2006. The U.K. government on Monday announced that French-owned EDF would build the first new British nuclear power station in 20 years. Lefteris Pitarakis/AP hide caption

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Much To Smile About? Iranian President Hasan Rouhani prepares to address the 68th session of the U.N. General Assembly on Tuesday. Frank Franklin II/AP hide caption

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North Korean leader Kim Jong Un (right) claps during a ceremony unveiling statues honoring his grandfather and father, Kim Il Sung and Kim Jong Il, respectively, in Pyongyang last April. Ed Jones/AFP/Getty Images hide caption

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Iranian Foreign Minister Ali Akbar Salehi speaks to reporters on the third day of the 49th Munich Security Conference on Sunday. Tobias Hase/AP hide caption

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The Fukushima Power Plant in Japan had three safety measures in place to make sure the fuel rods inside the nuclear reactor do not overheat. For various reasons attributed to the earthquake that triggered a tsunami, the measures failed. bagalute/flickr hide caption

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