MARINE MOUNTAIN WARFARE TRAINING CENTER, Calif. (AP) — Hunkered down behind a wall of snow, two U.S. Marines melt slush to make drinking water after spending the night digging out a defensive position high in the Sierra Nevada. Their laminated targeting map is wedged into the ice just below the machine gun.

Nearly 8,000 feet (2,440 meters) up at a training center in the California mountains, the air is thin, the snow is chest high and the temperature is plunging. But other Marines just a few kilometers away are preparing to attack, and forces on both sides must be able to battle the enemy and the unforgiving environment.

The exercise is designed to train troops for the next war — one the U.S. believes will be against a more capable, high-tech enemy like Russia, North Korea or China. The weather conditions on the mountain mimic the kind of frigid fight that forces could face in one of those future hotspots.

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