NEW YORK, NY - NOVEMBER 03: Republican presidential candidate Donald Trump speaks at a news conference before a public signing for his new book "Crippled America: How to Make America Great Again," at the Trump Tower Atrium on November 3, 2015 in New York City. According to a new poll, Ben Carson, the retired neurosurgeon, has pulled ahead of Trump with 29% of Republican primary voters. (Photo by Spencer Platt/Getty Images)
WASHINGTON, DC - MARCH 30: U.S. President Barack Obama listens as Vice President Joe Biden speaks during the Easter Prayer Breakfast at the White House on March 30, 2016 in Washington, D.C. (Photo by )
DE PERE, WI - MARCH 30: Republican presidential candidate Donald Trump walks out and waves to speak during a campaign event at St. Norbert College in De Pere, WI on Wednesday March 30, 2016. (Photo by )
Soldiers stand guard in front of the central train station on November 22, 2015 in Brussels, as the Belgian capital remained on the highest security alert level over fears of a Paris-style attack. / AFP / EMMANUEL DUNAND (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images)
IDOMENI, GREECE - FEBRUARY 29: Refugees break the fence on the Greek-Macedonia border on February 29, 2016 in Idomeni, Greece. A group of refugees forced the gate in an attempt to enter Macedonia. 7 refugees were injured during the riot. Tear gas and sound grenades were fired to clear the railway. The transit camp has become overcrowded as refugees continue to arrive from Athens and the Greek Islands. Macedonia opened its border with Greece allowing 580 refugees a day to cross into the country. According to local authorities 7000 refugees and migrants, mostly from Syria, remain stuck at the border as they wait to enter Macedonia to journey to Western Europe. (Photo by )
Pigeons stand on a statue of late Soviet dictator Josef Stalin in the storage of a foundry, on April 15, 2013 in Tirana. The bronze of the communist era statues is used to cast new artworks. AFP PHOTO / GENT SHKULLAKU (Photo credit should read )
Business students attend a lecture at the Aula Magna auditorium at the Stockholm University on October 30, 2012. Stockholm University has over 36,000 students at four faculties, making it one of the largest universities in Scandinavia. AFP PHOTO / JONATHAN NACKSTRAND (Photo credit should read JONATHAN NACKSTRAND/AFP/Getty Images)
during the final day of the Republican National Convention at the Tampa Bay Times Forum on August 30, 2012 in Tampa, Florida. Former Massachusetts Gov. Mitt Romney was nominated as the Republican presidential candidate during the RNC which will conclude today.
US President Barack Obama shakes hands with Israeli Prime Minister Benjamin Netanyahu during a bilateral meeting September 21, 2011 at the United Nations in New York City. AFP PHOTO/Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)
ARLINGTON, VA - JULY 6: (AFP OUT) U.S. President Barack Obama delivers remarks after meeting with members of his national security team concerning ISIS at the Pentagon July 6, 2015 in Arlington, Virginia. Obama announced the U.S. military is making progress against the Islamic State in Iraq and Syria. (Photo by Drew Angerer - Pool/Getty Images)
MILWAUKEE, WI - NOVEMBER 10: Presidential candidates Ohio Governor John Kasich (L-R), speaks while Jeb Bush, Sen. Marco Rubio (R-FL), Donald Trump, Ben Carson, and Ted Cruz (R-TX) take part in the Republican Presidential Debate sponsored by Fox Business and the Wall Street Journal at the Milwaukee Theatre November 10, 2015 in Milwaukee, Wisconsin. The fourth Republican debate is held in two parts, one main debate for the top eight candidates, and another for four other candidates lower in the current polls. (Photo by Scott Olson/Getty Images)
WASHINGTON, DC - NOVEMBER 25: U.S. President Barack Obama (L) "pardons" Abe, a 42-pound male turkey during a ceremony with National Turkey Federation Chairman Jihad Douglas (2nd L), turkey farmer Joe Hedden and Obama's daughters Sasha and Malia in the Rose Garden at the White House November 25, 2015 in Washington, DC. In a tradition dating back to 1947, the president pardons a turkey, sparing the tom -- and his alternate -- from becoming a Thanksgiving Day feast. This year, Americans were asked to choose which of two turkeys would be pardoned and to cast their votes on Twitter. (Photo by Chip Somodevilla/Getty Images)
A sign reading 'Peace for Paris' is seen as people gather around the Monument a la Republique, at the Place de la Republique in Paris, on November 15, 2015, two days after a series of deadly attacks. Islamic State jihadists claimed a series of coordinated attacks by gunmen and suicide bombers in Paris on November 13 that killed at least 128 people in scenes of carnage at a concert hall, restaurants and the national stadium. AFP PHOTO / PATRICK KOVARIK (Photo credit should read PATRICK KOVARIK/AFP/Getty Images)
A street vendor sells scarves of Turkish President Recep Taqyyip Erdogan, as supporters wait for the Turkish Prime Minister Ahmet Davutoglu (unseen) at the Istanbul Ataturk airport on November 3, 2015 in Istanbul. Turkey's long dominant Justice and Development Party (AKP) scored a stunning election success at the weekend with a vote that returned it to single-party rule after months of political uncertainty. The result is likely to bolster strongman President Recep Tayyip Erdogan as he seeks to expand his powers, but analysts warn it could further exacerbate deep rifts in Turkish society. AFP PHOTO / OZAN KOSE (Photo credit should read OZAN KOSE/AFP/Getty Images)
