Armed man stand at entrance of the naval headquarters in Sevastopol, March 19, 2014. Around a dozen Ukrainian servicemen, unarmed and in civilian clothes, walked out of the Ukrainian naval headquarters in the Crimean port of Sevastopol on Wednesday after it was taken over by pro-Russian forces, a Reuters witness said. (Photo by Baz Ratner/Reuters)

A girl with Russian national flags painted on her cheeks takes part in celebrations marking the first anniversary of Russia's annexation of Crimea, in central Simferopol March 16, 2015. Russia marks one year anniversary of annexation of Ukraine's Crimea peninsula this week. (Photo by Maxim Shemetov/Reuters)

A tank rolls out from a ship on a landing operation during military drills at the Black Sea coast, Crimea, Friday, September 9, 2016. Russia has deployed cruise missiles, multiple rocket launchers, tanks and its latest anti-aircraft system at massive military drills in Crimea. The drills which began across southern Russia and Crimea earlier this week and involve over 120,000 troops are some of the largest exercises Russia has held for years. (Photo by Pavel Golovkin/AP Photo)

Workers adjust rails at the bed of a drained area of a lake used for the production of salt at the Sasyk-Sivash lake near the city of Yevpatoria, Crimea, September 25, 2015. The area has a long tradition of salt production, prepared from salt flats flooded with water from the Black Sea. (Photo by Pavel Rebrov/Reuters)

A train drives along a field at a salt production site at the Sasyk-Sivash lake near the city of Yevpatoria, Crimea, November 14, 2017. A saltwater lagoon known as Lake Sasyk-Sivash on Ukraine's Crimea peninsula is the source of a rare resource: pink salt. The mineral is tinted by tiny algae that produce the pigment beta-carotene. Each autumn, seasonal workers collect thousands of tons of pink salt for processing and export. (Photo by Pavel Rebrov/Reuters)

Civilians are led by members of pro-Russian self-defence units as they run outside a military base during an assault in the Crimean town of Belbek near Sevastopol March 22, 2014. Russian troops forced their way into a Ukrainian airbase in Crimea with armored vehicles, automatic fire and stun grenades on Saturday, injuring a Ukrainian serviceman and detaining the base's commander for talks. (Photo by Vasily Fedosenko/Reuters)

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)

A young girls holds a ballot during the Greek referendum in Athens on July 5, 2015. Greek voters headed to the polls today to vote in a historic, tightly fought referendum on whether to accept worsening austerity in exchange for more bailout funds, in a gamble that could see it crash out of the euro. (Photo by Aris Messinis/AFP Photo)