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)

A member of the “Bloco Ultima Hora” group gets off a boat during Carnival of the Waters, where costumed and colorful boats navigate the river Tentem, around the islands near the city of Cameta, Brazil on February 8, 2018. (Photo by Ueslei Marcelino/Reuters)

Members of the Colombian Navy stand guard on top of a seized submarine built by drug smugglers in a makeshift shipyard in Timbiqui, department of Cauca February 14, 2011. Colombian authorities said the submersible craft was to be used to transport 8 tons of cocaine illegally into Mexico. (Photo by Jaime Saldarriaga/Reuters)

A mechanic assembles a BMW C evolution electric maxi-scooter at the BMW Berlin motorcycle plant February 23, 2015. The storage capacity of the BMW C evolution's high-voltage 8 kWh battery provides a range of up to 100 kilometres and a maximum speed of 120 km/h. (Photo by Fabrizio Bensch/Reuters)

Women dressed in traditional Chinese costumes wait perform in celebration of the Chinese New Year at the Nankinmachi square, China Town on February 8, 2016 in Kobe, Japan. In Nankinmachi, the district known as Kobe Chinatown, tourists enjoyed Chinese food, lion dance and the parade organized to celebrate the Lunar New Year. (Photo by Buddhika Weerasinghe/Getty Images)

Rita Ora attends the World Premiere of JEREMY SCOTT: THE PEOPLE'S DESIGNER, presented by The Vladar Company and Quintessentially at the TCL Chinese Theatre on Tuesday, September 8, 2015, in Hollywood, Calif. (Photo by Matt Sayles/Invision for The Vladar Company/AP Images)

Participants of the Sarenza High Heel Race 2015 warm up prior to the race during a party of the online shoe store, in Paris, Thursday, October 15, 2015. Competitors in teams of three girls race wearing shoes with more than 8 cm-high heels. (Photo by Francois Mori/AP Photo)

A worker looks on with his camel as he waits for tourists at the Giza Pyramids on the outskirts of Cairo, Egypt, November 8, 2015. Egypt's Tourism Minister Hesham Zaazou said Cairo regretted the suspension of flights and was doing all it could to secure its airports and tourist sites, adding that he would fly to Sharm al-Sheikh to oversee measures to support tourists there. (Photo by Amr Abdallah Dalsh/Reuters)