A tourist stands on a paddle boat near soldiers taking part on a military and police drill in preparation for the temporary closure of the holiday island Boracay in Philippines on April 24, 2018. (Photo by Erik De Castro/Reuters)

Servicewomen march during a rehearsal for the Independence Day military parade in central Kiev, Ukraine on August 20, 2018. (Photo by Gleb Garanich/Reuters)

MiG-15 jet fighters are pictured in Kucova Air Base in Kucova, Albania on October 3, 2018. Albania retired its 224 Soviet- and Chinese-made MiGs in 2005, and since 2009 NATO neighbors Italy and Greece monitor its airspace. That led to economic decline in and around Kucova, which was called “Stalin City” during the era of Communist rule. (Photo by Florion Goga/Reuters)

Students from St Andrews University are covered in foam as they take part in the traditional Raisin Weekend in the Lower College Lawn, at St Andrews in Scotland on October 22, 2018. The “raisin weekend” stems from a gift of raisins (now flour and foam) traditionally given by a first year student to their academic “parents” in gratitude for their guidance. (Photo by Russell Cheyne/Reuters)

A South Korean marine in action during their regular drill on Yeonpyeong Island, South Korea November 1, 2018. (Photo by Jeon Heon-Kyun/Pool via Reuters)

A man passes at the displayed art installation “Middle way” by Romanian artist Bogdan Rata in Kiev, Ukraine, Tuesday, November 20, 2018. The monument set on the central Kiev street of Khreshchatyk, at the place of Vladimir Lenin monument which was destroyed in 2013 during the Maidan events. (Photo by Efrem Lukatsky/AP Photo)

Tourists watch illuminated snow sculptures during the 31st Harbin Sun Island International Snow Sculpture Art Exposition on January 4, 2019 in Harbin, Heilongjiang Province of China. The 31st Sun Island International Snow Sculpture Art Exposition officially opened to public on December 29. (Photo by VCG/VCG via Getty Images)

The Swiss Air Force Patrouille Suisse aerobatic team performs during the men's downhill race at the Alpine Skiing FIS Ski World Cup in Wengen, Switzerland, Saturday, January 19, 2019. (Photo by Anthony Anex/Keystone via AP Photo)