Police search the area near a destroyed billboard reading "Crimea is Ukraine!" following an explosion in Odessa on June 12. Alexey Kravtsov/AFP/Getty Images hide caption

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Ukrainian national guardsmen practice protecting and recovering wounded comrades as American military trainers watch. Corey Flintoff/NPR hide caption

itoggle caption Corey Flintoff/NPR

Mikheil Saakashvili (center) is the former president of Georgia, which waged a brief war with Russia in 2008. Last month, Ukrainian President Petro Poroshenko (left) named Saakashvili the governor of Odessa, the port city in Ukraine, a country waging its own battle with Russia. The two are shown in Odessa on May 30. Mykola Lazarenko/Presidential Press Service Pool/AP hide caption

itoggle caption Mykola Lazarenko/Presidential Press Service Pool/AP

Visitors check out the Soviet-era metro cars exhibited at the Partizanskaya subway station in Moscow, as part of festivities marking the subway system's 80th anniversary. Pavel Golovkin/AP hide caption

itoggle caption Pavel Golovkin/AP

Russian military personnel march in Moscow's Red Square during a rehearsal Thursday for the Victory Day military parade that will take place Saturday to celebrate the 70th anniversary of the victory over Nazi Germany in World War II. Ivan Sekretarev/AP hide caption

itoggle caption Ivan Sekretarev/AP

Refugees from different cities of the Donetsk region controlled by pro-Russia separatists stay March 12 in a center for refugees in the eastern Ukrainian city of Slavyansk. The cease-fire in eastern Ukraine between Kiev's forces and pro-Russian rebels has been tenuous at best, and residents of the region continue to flee; 1.2 million have been displaced by the fighting. Sergei Supinsky/AFP/Getty Images hide caption

itoggle caption Sergei Supinsky/AFP/Getty Images