First graders attend a festive ceremony to mark the start of another school year in Slaviansk, September 1, 2014. September 1 marks the start of a new academic year for students in Ukraine. (Photo by Gleb Garanich/Reuters)

Members of the U.S. Army 173rd Airborne Brigade stand at attention as a Ukrainian folk dance group performs at the opening ceremony of the “Rapid Trident” NATO military exercises on September 15, 2014 near Yavorov, Ukraine. The two-week exercises include participating units from a variety of NATO and NATO-associate countries as well as Ukrainian troops. Meanwhile fighting between pro-Russian separatists and Ukrainian armed foces has flared again in eastern Ukraine in a battle for the control of Donetsk airport despite the tenuous ceasefire. (Photo by Sean Gallup/Getty Images)

A pro-Russian supporter with the Russian national flag on her shoulders takes part in a meeting in Simferopol, March 6, 2014. Crimea's parliament voted to join Russia on Thursday and its Moscow-backed government set a referendum within 10 days on the decision in a dramatic escalation of the crisis over the Ukrainian Black Sea peninsula. (Photo by Vasily Fedosenko/Reuters)

Lawmakers fight around the rostrum during the first session of Ukraine's newly elected parliament in Kiev, Ukraine, December 13, 2012. (Photo by Sergei Chuzavkov/Associated Press)

A man dressed as the “Star Wars” character Darth Vader sits on a bench in central Lviv, Ukraine, November 24, 2016. (Photo by Gleb Garanich/Reuters)

A Ukrainian serviceman is seen at his position on the front line in Krasnogorivka near Donetsk, Ukraine, August 12, 2016. (Photo by Gleb Garanich/Reuters)

A girl reacts during a rehearsal for the Independence Day military parade in central Kiev, Ukraine, August 19, 2016. (Photo by Valentyn Ogirenko/Reuters)

Local residents dressed in costumes perform during celebrations for the Malanka holiday in the village of Krasnoilsk in the Chernivtsi region of Ukraine, January 14, 2016. The Malanka traditional holiday is more popular in the western regions of the country and is also known as the Old New Year celebrated on January 13 and 14 – St. Basil's and St. Melania's Day, according to the old Julian calendar. During the celebrations, youngsters and adults wear traditional carnival costumes and masks, and visit local houses while singing carols, playing pranks or performing short plays. (Photo by Valentyn Ogirenko/Reuters)