A Ukrainian serviceman walks an empty street in the front line city of Bakhmut, in Donetsk region, Ukraine on February 25, 2023. (Photo by Serhii Nuzhnenko/Radio Free Europe/Radio Liberty)

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 U.S. Army crew chief flying on board a CH-47F Chinook helicopter observes the successful test of flares during a training flight in Afghanistan, March 14, 2018. (Photo by Tech. Sgt. Gregory Brook/Reuters/U.S. Air Force)

A young YPJ recruit (in pink) arrives to the training base for her first day in training near Derek City, Syria. The YPJ schedule is demanding and requires discipline – new soldiers in training get about 6 hours of sleep a night and wake up at 4 AM to begin exercising; afterwards, their day consists of a full schedule of drills and classroom lessons. Before joining the YPJ many of the girls had never participated in physical activity or sports before. (Photo by Erin Trieb/NBC News)

Ukrainian servicemen of the 28th Separate Mechanised Brigade fires a 122mm mortar towards Russian positions at the front line, near Bakhmut, Donetsk region, Ukraine, Sunday, March 3, 2024. (Photo by Efrem Lukatsky/AP Photo)

A Ukrainian Army liaison officer Vira, 22, plays with her rat Malyi (Tiny) at her positions near a frontline, in Donetsk region, Ukraine, on March 8, 2024. (Photo by Inna Varenytsia/Reuters)

Ukrainian soldiers from the assault brigade inflict fire damage with a 120 mm mortar while supporting the assault operations of the infantry on April 19, 2024 in Ukraine. The country's Prime Minister Denys Shmyhal has warned its allies that if more military aid for Ukraine is not approved soon, such as the long-stalled aid package from the United States, it could usher in a “Third World War”. (Photo by Kostiantyn Liberov/Libkos/Getty Images)

A Ukrainian serviceman from an anti-drone mobile air defence unit uses his mobile device near a ZU-23-2 anti aircraft cannon as he waits for Russian kamikaze drones, amid Russia's attack on Ukraine, in Kherson region, Ukraine on June 11, 2024. (Photo by Ivan Antypenko/Reuters)