Tactics reminiscent of the early American frontier days are now being used in Vietnam. Lieutenant Commander Donald D. Sheppard, UBN, of Coronado, California, aims a flaming arrow at a bamboo hut concealing a fortified Viet Cong bunker on the banks of the Bassac River, Vietnam on December 8, 1967. (Photo by AP Photo)

Riot police clash with demonstrators protesting against proposed pension reforms outside the Congress in Buenos Aires on December 18, 2017. Protesters angry at proposed pension and welfare reforms attacked police close to Argentina's congress building in Buenos Aires on Monday, the second protest in a week to turn violent. Activists lobbed stones, bottles and firecrackers at police as huge crowds demonstrated against pension reforms proposed by the center-right government of President Mauricio Macri. (Photo by Eitan Abramovich/AFP Photo)

Revellers out and about in Newcastle, England on “Black Eye Friday” or “Mad Friday” on December 22, 2017 as people across the country celebrate the start of the Christmas break by hitting bars, pubs and clubs. This partygoer had so much fun she looks lost. (Photo by Craig Connor/North News and Pictures)

An exhausted Rohingya refugee woman touches the shore after crossing the Bangladesh-Myanmar border by boat through the Bay of Bengal, in Shah Porir Dwip, Bangladesh, September 11, 2017. (Photo by Danish Siddiqui/Reuters)

Filipino children play as they are doing caroling activities on the street near an airport, days before Christmas in Manila, Philippines, 20 December 2017. Filipinos celebrate the longest Christmas in the world which starts as early as September every year. (Photo by Francis R. Malasig/EPA/EFE)

Charlotte Caslick of Australia is tackled by Jasmine Joyce of Wales during the Rugby Sevens Women's Pool B match between Australia and Wales on day nine of the Gold Coast 2018 Commonwealth Games at Robina Stadium on April 13, 2018 on the Gold Coast, Australia. (Photo by Dan Mullan/Getty Images)

People participate in the first day of Thingyan Water Festival in Naypyitaw, Myanmar on April 13, 2018. The annual water festival, known as Thingyan, features large groups of people congregating to celebrate the by splashing water and throwing powder at each other's faces as a symbol of cleansing and washing away the sins from the old year. It marks the start of the traditional New Year and is similarly celebrated in countries such as Myanmar, Thailand, Laos and Cambodia. (Photo by Hein Htet/EPA/EFE/Rex Features/Shutterstock)

Sister Kate and Sister Claire pose on the beach to promote the documentary film “Breaking Habits?” at the Cannes Film Festival on May 09, 2018 in Cannes, France. (Photo by Regis Duvignau/Reuters)