Fighting at sea level is tough, but it doesn't get any easier thousands of feet up a mountain. The military prepares for fights at altitude by training extensively in challenging weather and terrain. Here are 16 photos that show what it's like.
1. Narrow passes of ice-covered rocks
2. Getting down the mountain is faster – but more dangerous – than climbing up.
3. Helicopters can make a big difference when they're available.
4. For getting across the soft snow, skis and snowshoes are handy.
5. Sleds can carry extra gear that won't fit in a pack.
6. The Marines train on both riding horses and mules, and use them as pack animals.
7. When the snow is melted, standard boots can get the job done.
8. But again, a controlled fall is the easiest way to travel.
9. Traveling across the rock face takes skill and trust in the equipment.
10. Getting around the mountain isn't enough. Troops have to fight up there.
11. The terrain makes it hard for troops to maneuver on well-placed snipers, so they can be especially effective.
12. Working as a team is key in the mountains.
13. The "Red Hats," trainers who specialize in mountain operations, know to move as a group.
14. Even on the ropes, it's best if the team can stay together.
15. You get cool points for taking photos on top of a mountain, but you would get more if you removed the blank adapters first.