Two robotic legged squad support system (LS3) machines by the Defense Advanced Research Project Agency follow a technician during a demonstration at Joint Base Myer-Henderson Hall, Virginia, on September 10, 2012. (U.S. Marine Corps photo by Sgt. Mallory S. VanderSchans via The Atlantic)

Alejandro Ccasa prays after waiting three days next to an empty oxygen tank for his uncle who has COVID-19 outside a refill shop where he is the first in line before it opens in Callao, Peru, early Tuesday, February 2, 2021. Ccasa said his family has one large tank and it gives about four hours of oxygen therapy. (Photo by Martin Mejia/AP Photo)

A Ukrainian serviceman smokes a cigarette at his position at the frontline near Bakhmut, Donetsk region, Ukraine, Wednesday, January 11, 2023. (Photo by Evgeniy Maloletka/AP Photo)

A cat sits on the shoulder of Ukrainian serviceman Mykyta of the 93rd separate mechanized brigade at a rest house near the front line in the Donetsk region on December 25, 2023. (Photo by Thomas Peter/Reuters)

New York Police Department tactical police officers stand guard near the New York Stock Exchange on September 9, 2011 in New York City. Officials are stepping up security in New York and Washington D.C. a day after U.S. officials received a credible but unconfirmed terror threat to utilize car bombs on bridges or tunnels in New York or Washington. (Photo by Justin Sullivan/Getty Images)

Artem, a serviceman of infantry battalion of the 61st mechanised brigade, pets a dog in a trench at a position near the frontline, in Kharkiv region, Ukraine on January 6, 2024. (Photo by Sofiia Gatilova/Reuters)

A couple covered in foam kiss as they take part in the traditional “Raisin Weekend” in the Lower College Lawn, at St Andrews in Scotland, Britain on October 17, 2022. (Photo by Russell Cheyne/Reuters)

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)