ISLAMABAD — The use of drones in Pakistan normally brings to mind images of U.S. spy planes attacking tribal areas. But drones are being used to capture a different kind of picture in the country — showing some of the world’s highest mountains being scaled by world-class climbers through some of Earth’s thinnest air.

Drones, or remote-controlled aircraft, have long been the domain of the American military and are used extensively in Pakistan’s tribal areas near the Afghanistan border to spy on and target militants. Recently, however, civilians have increasingly turned to drones to shoot groundbreaking footage of adventure sports.

This past summer, a Swiss expedition used remote-controlled helicopters to shoot rare footage of climbers on the Karakoram, one of the world’s most demanding and formidable mountain ranges.

“People are going to see footage from the Karakoram that no human being has ever seen,” said Corey Rich, a photographer and videographer from Lake Tahoe, Calif., who was on the expedition.

The expedition was a joint project between outdoor clothing and equipment company Mammut and Dedicam, a firm that specializes in using remote-controlled helicopters to shoot video. Their goal: to document world-class mountaineer David Lama and his climbing partner Peter Ortner as they climbed Trango Tower.

The sheer granite tower in the Baltoro Glacier is more than 19,685 feet above sea level and is one of the most technically difficult climbs in the world.

Filmmakers long have used helicopters to capture aerial footage of climbers — as well as other extreme-sport athletes such as surfers and skiers —that is hard to capture from the ground. But helicopters are costly and can be dangerous if they crash or get too close to the people on the ground. Additionally, their beating rotors often kick up dust, snow and wind — and can push climbers off balance.

Drones, which can weigh just a few pounds and cost between $1,000 and $40,000, are a fraction of the size and cost of the helicopters traditionally used in adventure photography. Newer models tend to have all of their rotors facing into the sky, making them look a bit like a mechanical flying spider or insect.

The main concern for the summertime expedition was how — and if — the drone would perform in Pakistan’s rugged conditions and high altitude.

“The main challenge was that the air is much thinner, and we didn’t know how the flight controls would work with this and the propellers and motors,” said drone operator Remo Masina, from Lucerne, Switzerland.

He brought two drones on the Pakistan expedition — one with four propellers and another with six. From the ground, he flew them with a hand-held console that resembles a video-game console, and wore goggles to let him see the camera’s view.

Another challenge was to find the climbers on the mountain. Tracing the planned trek route, Masina directed the drone up the mountain until he spotted them — more than a mile away. The result was stunning images of the Karakoram and the climbers making it to the top.

Experienced climbers say the Karakoram puts the rest of the world’s mountain ranges to shame. Neighboring Nepal has Everest, the tallest mountain in the world, but Pakistan has four of the world’s 14 peaks that soar to more than 26,246 feet above sea level, including the second-highest mountain on earth, K-2.

Lama and Ortner said climbing the legendary Pakistan mountains was an amazing experience.

“Here, there are so many mountains, and so many difficult mountains, and mountains that haven’t been climbed,” Lama said. “That’s probably why the Karakoram is known as paradise for us.”