Željava Air Base, situated on the border between Croatia and Bosnia and Herzegovina under Plješevica Mountain, near the city of Bihać, Bosnia, was the largest underground airport and military air base in the former Yugoslavia, and one of the largest in Europe. (Photo by Thomas Windisch/Exclusivepix Media)

A woman and a child make a bonfire at a makeshift camp for migrants and refugees at the Greek-Macedonian border near the village of Idomeni, Greece, April 1, 2016. (Photo by Marko Djurica/Reuters)

Border Security Force (BSF) soldiers ride their camels as they take part in a rehearsal for a road show ahead of the visit of U.S. President Donald Trump, in Ahmedabad, India, February 21, 2020. (Photo by Amit Dave/Reuters)

A United States Border Patrol agent on horseback tries to stop a Haitian migrant from entering an encampment on the banks of the Rio Grande near the Acuna Del Rio International Bridge in Del Rio, Texas on September 19, 2021. The United States said Saturday it would ramp up deportation flights for thousands of migrants who flooded into the Texas border city of Del Rio, as authorities scramble to alleviate a burgeoning crisis for President Joe Biden's administration. (Photo by Paul Ratje/AFP Photo)

Pakistani Rangers (black) and Indian Border Security Force personnel (brown) perform perform during the daily beating of the retreat ceremony at the India- Pakistan Wagah Border Post, some 35 kms west of Amritsar on August 14, 2017. Pakistan celebrates its independence on August 14, one day before India' s independence day on August 15. (Photo by Narinder Nanu/AFP Photo)

Undated image released Monday February 17, 2020, by Irish Coast Guard showing the abandoned cargo ship MV Alta, that has washed up on the coast of County Cork, near Ballycotton, southern Ireland. The MV Alta is believed to have had 10 crew members aboard who were rescued by the US Coast Guard. Since September 2018, the ship has been drifting with no crew aboard, and it was last seen off the coast of West Africa before being washed up in southern Ireland during Storm Dennis. (Photo by Irish Coast Guard via AP Photo)

A child coughs as migrants and refugees run away after Macedonian police fired tear gas at hundreds of Iraqi and Syrian migrants who tried to break through the Greek border fence in Idomeni, on February 29, 2016. Greek police said more than 6,000 people were massed at the border, in a buildup triggered by Austria and Balkan states capping the numbers of migrants entering their territory. (Photo by Louisa Gouliamaki/AFP Photo)

Migrants bathe in the Huixtla River, Chiapas state, Mexico, Tuesday, October 26, 2021, as they take a day of rest before continuing their trek across southern Mexico to the U.S. border. (Photo by Marco Ugarte/AP Photo)