U.S. Marines conduct a simulated assault during a force on force training event during exercise Northern Viper on Yausubetsu Training Area, Hokkaido, Japan, Feb. 7, 2020. - U.S. Marines conduct a simulated assault during a force on force training event during exercise Northern Viper on Yausubetsu Training Area, Hokkaido, Japan, Feb. 7, 2020.