Ingots of 99.99 percent pure silver are cast at the Krastsvetmet Krasnoyarsk non-ferrous metals plant in the Siberian city of Krasnoyarsk, Russia, June 5, 2015. Krastsvetmet is one of the world's largest players in the precious metals industry. REUTERS/Ilya Naymushin

This undated handout photo received from the Antarctic Ocean Alliance on October 28, 2016 shows a adelie penguin jumping onto the ice in the Ross Sea in Antarctica. The world's largest marine reserve aimed at protecting the pristine wilderness of Antarctica will be created after a “momentous” agreement was finally reached on October 28, 2016 with Russia dropping its long-held opposition. (Photo by John Weller/AFP Photo/Antarctic Ocean Alliance)

A female Marine prepares to throw a practice grenade during Marine Combat Training (MCT) on February 21, 2013 at Camp Lejeune, North Carolina. Since 1988 all non-infantry enlisted male Marines have been required to complete 29 days of basic combat skills training at MCT after graduating from boot camp. MCT has been required for all enlisted female Marines since 1997. About six percent of enlisted Marines are female. (Photo by Scott Olson)

Philippine Marines from the Naval Special Operations Group (NAVSOG) storm the beach to simulate an “extraction” of a kidnapped victim as they kick off a five-day amphibious military exercise at the Philippine Marines training center in Ternate, Cavite province, about 50 miles (80kms) south of Manila, Philippines Thursday, September 24, 2015. The naval exercise dubbed PAGSISIKAP 2015 is aimed at enhancing capability of their fleet and forces as well as to strengthen interoperability of the Marines. (Photo by Bullit Marquez/AP Photo)

A participant tries to tie a steer during the Russian Rodeo in the village of Kotliakovo, Bryansk region, southeast of Moscow, Russia, September 12, 2015. The competition was organised by privately held Miratorg, one of the leading Russia's meat producers, between the divisions of the agricultural holding. (Photo by Maxim Shemetov/Reuters)

An employee works on a glass sphere for Christmas and New Year decoration at the “Biryusinka” toy factory, which has been producing decorations and toys for the festive season since 1942, in the Siberian city of Krasnoyarsk, Russia, November 16, 2016. (Photo by Ilya Naymushin/Reuters)

Sergey, one of the participants of PARTISAN courses, poses for a portrait in an abandoned building in Olgino, St. Petersburg, Russia on November 23, 2016. Sergey came to St. Petersburg from the city of Cheliabinsk to attend an intensive seven-day program. Sergey is a businessman, a traveller and a blogger. His another passion are “men's hobbies”, that's why he participated in the paramilitary courses. (Photo by Alexander Aksakov/The Washington Post)

Cars pass a tank position close to the Russian border near the Ukrainian city of Kharkiv March 24, 2014. U.S. President Barack Obama sought support from European allies and China on Monday to isolate Russia over its seizure of Crimea, and Ukraine told its remaining troops to leave the region after Russian forces overran one of Kiev's last bases there. (Photo by Dmitry Neymyrok/Reuters)