Part 3 of a 4-part series.

GILGIT AND KOHISTAN DISTRICT, Pakistan -- "They've been very grateful, from my experience."

Army Sgt. Jesus Ramos quickly dismisses concerns back home that he and other U.S. forces participating in flood relief operations in Pakistan are facing hostility in what is frequently depicted as an anti-American nation.

"When we're downloading, they come up to you, shake your hand, smiles on their faces," he explains while resting before another full day of relief flights to the rugged north.

Some 12 weeks since the onset of devastating flash floods left a half-million Pakistanis stranded, U.S. forces are still actively assisting the Pakistani military with delivering aid to populations in need. They are flying food and materials to northern areas cut off after flash flooding washed out roads and bridges.

Though they are here at the invitation of Pakistan and can be forced to leave as soon as the government orders them out, U.S. embassy officials say they expect troops to be here doing this work until at least November.

The troops involved say they have all trained heavily in disaster relief work since enlisting, but many also admit that they never expected to actually be putting the training to work, expecting instead to be engaged in combat. Some service members with 20 years of experience say their Pakistan deployment is their first-ever experience with humanitarian operations.

But Pentagon officials believe that future service in the U.S. armed forces could be characterized more by the type of all-day back-and-forth airlifts to flood-stricken parts of Pakistan than by the counterinsurgency battles winding down in Iraq but still raging in nearby Afghanistan.

A tryout for future climate-related missions

In February, the U.S. Department of Defense released a quadrennial defense review report that for the first time linked global warming directly to national security hazards. The report calls climate change an "accelerant of instability" that could increase the frequency and severity of natural disasters, taxing civilian disaster relief capabilities and requiring more regular military support.

DOD has been among the first on scene responding to a string of mass-casualty disasters caused by earthquakes, including the devastating quake in northern Pakistan in 2005. But many believe the Pakistan super-floods of 2010 represents the first time U.S. forces have been called into action in response to a major climate change disaster.

"We helped out with the [2004 Indian Ocean] tsunami a couple years ago, Haiti just this year," recalled Capt. Clark Noble, a helicopter pilot in an expeditionary unit of the Marine Corps. "It's now a regular part of our duties."

Riding with and interviewing the men and women engaged in efforts here shows that, for most enlisted personnel, relief work in foreign lands is among the most welcome and rewarding parts of their service. It's also almost as exhausting and stressful as combat, and not without its own levels of danger and deadly threats, especially in northern Pakistan.

"I wouldn't say that you're any more or less nervous; I'd just say that it's different," explained U.S. Army Chief Warrant Officer William French, a helicopter pilot comparing his service here to a tour in Iraq. "I'm not nearly as concerned about someone shooting at me, but I'm still always thinking of that."

U.S. military assistance in Pakistan's north consists of two main operations. The Marine Corps was flying C-130 airplanes from Chaklala Air Base near Islamabad to Gilgit and Skardu in Pakistani-administered Kashmir. This area finds itself isolated after the flood destroyed parts of the famous Karakoram Highway. The cities are world-renowned as launching pads for trekking expeditions into the scenic mountains and are used to hosting foreigners.

The C-130 missions to the north have since ended, but Marine and now Army Chinook and Black Hawk helicopters have also been flying in food and other aid to inaccessible parts of the Swat Valley and Kohistan from an air base in Ghazi. Swat was the scene of a massive Pakistan Army campaign against Taliban insurgents last year, and Kohistan is famous as an inaccessible, deeply impoverished and conservative mountainous corner that rarely sees foreign visitors.

Threading heavy loads through rocky valleys

The system is set up as a straightforward temporary logistics support operation, moving people and material as long as daylight lasts and security and weather conditions allow. The planes and helicopters move whatever the Pakistanis ask them to carry, including food, supplies, people and sometimes even livestock.

All military personnel said they have received a warm welcome.

"The first couple weeks, it seemed like people were pretty excited to receive our help," said Capt. Noble, who had been flying up and down the Swat Valley for a month. "Every time we dropped off stuff, 45 minutes later, when we come back, it was gone, so obviously people are using what we dropped off."

But the relative simplicity of their operation and the hospitality shown by their hosts masks the very real dangers that can be involved, most often just from the elevation and jagged terrain.

"For our airframes, we're flying them right at max gross weight, so there's a very narrow power margin," Army officer French explained. "There's very little margin for error to land, and that could be caused both by the weight of the aircraft, the altitude that we're flying at, and also the very narrow valleys."

After a refueling stop at a helipad in Pathan, Kohistan, a pair of Army Black Hawk helicopters made their way farther north up the Indus River Valley by the Kashmiri border. The smaller Black Hawks are needed here because there are very few convenient or workable landing spots -- at one point, the pilot set the helicopter down on a rocky ledge right next to raging whitewater rapids, the rotor spinning just a couple of feet from a massive rock-face wall.

The approach to Gilgit can be equally perilous, depending on the weather.

Regarded as one of the more dangerous airports in the world, the Gilgit landing can only be reached by flying through one narrow valley, negotiating a 90-degree turn left around a mountain into another valley and another 90-degree turn to the right to line up with the airfield. Any sign of bad weather, even slight fog, will see the air crew calling off the approach.

"You can't see down the direct line of sight to the field until you make it around this peak, which is a pretty high peak," said 1st Lt. Glenn Ryberg, a Marine Corps C-130 airplane pilot.

Guarded landings, but warm receptions

The terrain Ryberg and his crew must negotiate on a daily basis is harrowing. The view from the cockpit of the plane, already flying at 21,000 feet in elevation, shows mountains on both sides still towering well above it. When crews see that they are flying below these peaks, that's when they know they are at the "go/no-go" point, Ryberg said.

"Once you determine that it's OK to descend, which means there are no clouds in the valley, we'll come down on this corner, and that's really where you kind of make the final decision if you're going to continue," he explained. Ryberg added that the Marines are flying this route because the Air Force deemed it too dangerous for their pilots to try it, though he believed approval would come soon.

The noise of aircraft and security precautions made it impossible to ask locals how they felt about the assistance provided by U.S. troops. But the warm smiles and enthusiastic waves and handshakes traded at every drop-off point suggested that the affected communities are happy to get any help they can, regardless of who the donor is.

U.S. military personnel say that their work with Pakistani troops has also gone smoothly, with many of the links cemented during their joint response to Kashmir's 2005 earthquake crisis. Pakistani military officials agree, though some admitted to early problems after the government requested assistance in Swat and Kohistan, parts of which are still considered conflict zones.

Two Pakistan Army officers at the Pathan helipad complained of delays and administrative hurdles in the early days of the disaster response as officials at the Pentagon worried that their forces might come into contact with hostile armed insurgents.

The government has since put in place tight security protocols. Landing zones are secured ahead of time, and each helicopter is assigned two Pakistan Army commandos to guard the flights. The locals help to unload supplies, but every civilian is patted down and searched for weapons or explosives before they are allowed near the helicopters.

Exhausted crews give 22,000 free rides

But the threat of armed elements remains, meaning that not all relief drops go smoothly.

After landing in one remote spot of Kohistan, in a designated Provincially Administered Tribal Area, the Pakistani leader of a flight ordered a hasty evacuation after less than a minute on the ground, before any aid could be delivered. The order came after local tribesmen warned him and the security detail that Taliban or other armed men were hiding behind a hill near the landing spot, apparently waiting for offloading to begin to launch an ambush.

The abandoned drop left both Pakistani and American personnel upset, not because of the near miss but because the three dozen men and boys waiting at the site desperately needed the food on board.

"Look, it's not the first time it's happened," said Pakistan Army Capt. Asad Mehmood, the safety pilot during the trip and the same man who ordered the hasty retreat. Mehmood downplayed the incident, insisting that it would be resolved the next day with a better security assessment and other precautions.

Thus far, no relief flight has come under attack. Rather, it's much more common for a drop to get called off because a landing simply can't be made, either because of wind or a lack of space. "There are several areas that we've flown over where we can't land and you see them waving at us like 'We need food,'" said Sgt. Ramos. "There's really nothing you can do."

The real enemy is fatigue.

After a day of constant flying, refueling, and loading and offloading of aid, pilots and flight crews are too exhausted to speak. It's a months-long operation that runs 24 hours a day, with maintenance crews taking over at the end of the day and working all through the night repairing aircraft and reading them for the next day.

The flights from Ghazi, about two hours northwest of Islamabad, continue. To date, U.S. forces have helped deliver more than 16 million pounds of humanitarian relief and provided rides to over 22,000 flood victims.

All soldiers and Marines interviewed agree that the work is remarkably similar to logistic operations in combat zones, with the exception that flights are kept to designated routes, there are no nighttime flights, and the risk of getting shot at is much lower, though not completely gone. No one expressed disappointment with the assignment; rather, they expressed pleasant surprise at finding themselves in a relief operation rather than the typical combat or defense roles military recruits are told to expect.

That's good, because if the February Pentagon defense review on climate change threats is correct, then future U.S. military personnel may find themselves doing much more disaster relief work than fighting.

"When I first enlisted, I thought I was going straight off to Afghanistan or Iraq on a combat mission," said Army Spc. William Rose, a new arrival from Fort Wainwright, Alaska. "It's way better than what I expected."

Saadia Haq contributed to this report.

 Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500