A Russian ground staff member signals to the pilot of a Sukhoi Su-25 fighter jet at the Hmeymim air base near Latakia, Syria, in this handout photograph released by Russia's Defence Ministry October 22, 2015. (Photo by Reuters/Ministry of Defence of the Russian Federation)

Ivan Plakhuta, 54, the owner of a small workshop manufacturing valenki, Russian traditional footwear, rolls a valenok in the remote Siberian village of Bolshaya Rechka, located in Taiga area in the foothills of the Western Sayan Mountain Ridge in the Yermakovsky district of Krasnoyarsk region, Russia, November 10, 2015. (Photo by Ilya Naymushin/Reuters)

Paramedics carry an injured woman out from a subway station after a rush-hour subway train derailment, to be transported by a medical helicopter in Moscow, Russia, on Tuesday, July 15, 2014. A rush-hour subway train derailed in Moscow Tuesday, killing 20 people and injuring at least 150, emergency officials said. Several cars left the track in the tunnel after a power surge triggered an alarm, which caused the train to stop abruptly. (Photo by Ivan Sekretarev/AP Photo)

Vintage wine bottles dated from 1946 lay down in the wine cellar of the Massandra winery near Yalta, 28 March 2014 (Yalta is a resort city on the north coast of the Black Sea in the Autonomous Republic of Crimea, a territory recognized by a majority of countries as part of Ukraine and incorporated by Russia as the Republic of Crimea). Massandra winery has one of the largest wine collections in the world. (Photo by Sergei Ilnitsky/EPA)

In this handout image provided by Red Bull, Artem Silchenko of Russia dives from the 27 metre platform at training on Hong Island in the Andaman Sea during the final stop of the 2013 Red Bull Cliff Diving World Series on October 25, 2013 at Krabi, Thailand. (Photo by Romina Amato/Red Bull via Getty Images)

Students of the General Yermolov Cadet School take part in combined military training with members of a local youth military patriotic club at a boot camp of the Russkiye Vityazi (Russian Knights) military patriotic club in the village of Sengileyevskoye outside Stavropol, Russia February 8, 2017. (Photo by Eduard Korniyenko/Reuters)

Artist German Vinogradov acts in the performance of the burning of Maslenitsa tower, devoted to Pancake Week, a pagan holiday marking the end of winter, in the village of Nikola-Lenivets, Kaluga region, Russia, February 25, 2017. (Photo by Maxim Shemetov/Reuters)

A 2S5 Giatsint self- propelled gun fires during tactical exercises held by artillery detachments of the Russian Eastern Military District' s 5th Army at the Sergeyevsky training ground in Primorye Territory, Russia on March 21, 2017. Over 2500 servicemen practice combat skills received in 2017 winter training exercises. (Photo by Yuri Smityuk/TASS)