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)

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 wait to cross the Slovenia-Austria border in Sentilj, Slovenia, October 27, 2015. The first five border guards – all German – of 400 promised to Slovenia by fellow EU countries are expected to arrive on Wednesday to help channel a huge flow of migrants through the tiny Alpine state, its government said. Interior Ministry state secretary Bostjan Sefic also said 100-120 customs police would join Slovenian soldiers, regular police and private security firms in dealing with an influx that has strapped the country's limited resources. (Photo by Srdjan Zivulovic/Reuters)

In this Thursday, April 11, 2013 photo, North Korean female soldiers stand watch on the river bank of the North Korean town of Sinuiju, opposite to the Chinese border city of Dandong. (Photo by AP Photo)

An alligator is pictured stuck in the mud of the dry Pilcomayo river, which is facing its worst drought in almost two decades, on the border between Paraguay and Argentina, in Boqueron, July 3, 2016. (Photo by Jorge Adorno/Reuters)

African migrants stranded in Costa Rica walk near garbage on the Inter-American highway at the border between Costa Rica and Nicaragua, in Penas Blancas, Costa Rica, September 8, 2016. (Photo by Juan Carlos Ulate/Reuters)

Members of the Indian Border Security Force (BSF) demonstrate their skills on motor-bikes during the BSF Golden Jubilee Day celebration in New Delhi on December 1, 2015. (Photo by Money Sharma/AFP Photo)

Syrian refugees sit behind barbed wire as they wait to cross into Macedonia at the Greek-Macedonian border, near the village of Idomeni, August 21, 2015. (Photo by Yannis Behrakis/Reuters)