Corporal Zhang Chong, left first, who just comes back from a long home leave in the plain area, feels uncomfortable and has to breathe pure oxygen with the help of his peers during the patrol mission. Soldiers from a border defense company under the PLA Xinjiang Military Command (MC) stationed in Khunjerab Pass of the Pamir Plateau patrolled the China-Pakistan border at an altitude of 5283 meters in frigid weather conditions.