Vintage American history photo of a nuclear weapon test by the American military at Bikini Atoll, Micronesia on July 25, 1946. The explosion was part of Operation Crossroads. John Parrot/Stocktrek Images/Getty Images hide caption

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John Parrot/Stocktrek Images/Getty Images

President Donald Trump is joined by the Congressional leadership and his family before formally signing his cabinet nominations into law on Jan. 20 in the President's Room of the Senate on Capitol Hill in Washington. From left are, Vice President Mike Pence, the president's wife Melania Trump, their son Barron Trump, and House Speaker Paul Ryan. J. Scott Applewhite/AP hide caption

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J. Scott Applewhite/AP

At a March 3 Republican presidential primary debate, candidates (from left) Marco Rubio, Donald Trump, Ted Cruz and John Kasich appear on stage at Fox Theatre in Detroit. Rubio later dropped out of the race. Paul Sancya/AP hide caption

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Paul Sancya/AP

Diane, a 4-year-old chimpanzee, relaxes in the trees at the Chimp Haven sanctuary in Keithville, La., on Aug. 25, 2014. She is one of many chimps who have been moved here from the New Iberia Research Center in Lafayette, La. Brandon Wade/AP hide caption

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Brandon Wade/AP

Activists hold a banner reading "standing and decided for climate" during a demonstration near the Eiffel Tower in Paris on Dec. 12, 2015, during the United Nations Climate Change Conference. Matt Dunham/AP hide caption

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Matt Dunham/AP

French Foreign Minister and President of the COP21 Laurent Fabius (center) gives a thumbs up while U.N. Secretary-General Ban Ki-moon (left) and French President Francois Hollande applaud after the final meeting of the U.N. conference on climate change in Le Bourget, France, on Saturday. Francois Mori/AP hide caption

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Francois Mori/AP