Russian soldiers write home while serving on the Eastern Front during World War I, circa 1915. (Photo by Hulton Archive/Getty Images)

An Indian Sikh devotee spits fire as he performs during religious procession ahead of the birth anniversary of the first Sikh Guru or master, Sri Guru Nanak Dev Ji, the founder of Sikhism, in Jammu, the winter capital of Kashmir, India, 21 November 2018. The birth anniversary of Guru Nanak Dev Ji will be observed on 23 November 2018. (Photo by Jaipal Singh/EPA/EFE)

North Korean bodyguards run along a limousine transporting Kim Jong Un upon his arrival in Dong Dang, Vietnam, February 26, 2019. The second meeting of the US President and the North Korean leader, running from 27 to 28 February 2019, focuses on furthering steps towards achieving peace and complete denuclearization of the Korean peninsula. (Photo by Reuters/Stringer)

A woman poses for a photo in a vehicle parked on the street as a tourist attraction, in Bangkok, Thailand on July 29, 2019. (Photo by Soe Zeya Tun/Reuters)

Guests arrive at the red carpet for the movie “The Truth” (La Verite) presented in competition at the 76th Venice Film Festival, in Venice, Italy, August 28, 2019. (Photo by Yara Nardi/Reuters)

An aircraft passes the rising sun during take off at the international airport in Frankfurt, Germany, Monday, September 2, 2019. (Photo by Michael Probst/AP Photo)

Fans of the Brazilian heavy metal band Sepultura enjoy their showo at the main stage of Rock in Rio festival 2019 at the Olympic Park, Rio de Janeiro, Brazil, on October 4, 2019. The week-long Rock in Rio festival started September 27, with international stars as headliners, over 700,000 spectators and social actions including the preservation of the Amazon. (Photo by Mauro Pimentel/AFP Photo)

A female police officer stands in the street during an anti-government protest in Santiago, Chile, Saturday, October 26, 2019. Chile has been facing days of unrest, triggered by a relatively minor increase in subway fares. The protests have shaken a nation noted for economic stability over the past decades, which has seen steadily declining poverty despite persistent high rates of inequality. (Photo by Rodrigo Abd/AP Photo)