Oct. 6, 2009 -- The remote base in northern Afghanistan where eight U.S. soldiers were killed this weekend in a deadly battle was well-known inside the military as extremely vulnerable to attack since the day it opened in 2006, according to U.S. soldiers and government officials familiar with the area.

When a reporter visited the base a few months after it opened, soldiers stationed in Kamdesh complained the base's location low in a valley made most missions in the area difficult.

"We're primarily sitting ducks," said one soldier at the time.

Known as Camp Keating, the outpost was "not meant for engagements," said one senior State Department official assigned to Afghanistan, and brings "a sad and terrible conclusion" to a three-year effort to secure roads and connect the Nuristan province to the central government in Kabul.

The boulder strewn road that led into the valley was referred to by U.S. soldiers stationed there as "Ambush Alley."

In addition to the eight dead Americans, at least two Afghan Army officers were killed, with as many as a dozen Afghan National Policemen missing, according to military and Afghan officials.

The base, located less than 10 miles from the Pakistan border and nestled in the Hindu Kush mountains, was attacked almost every day for the first two months it was opened, hit by a constant stream of rocket-propelled grenades and small arms fire.

By the third or fourth month of the base's existence, resupply had been limited to nighttime helicopter flights because the daytime left helicopters and road convoys too exposed to insurgent attacks. That remained true through the weekend.

The base had several near-misses with enemy fire over the years. In 2006, all daytime helicopter flights landing at the valley floor were cancelled when an American Blackhawk was nearly hit with an incoming rocket as it was taking off. After the incident, helicopters were banned from landing anywhere but an observation post some three hours' walk above the base on a nearby ridgeline. Even then, helicopters filled with troops or equipment were rushed during offloading, as pilots were keen to take off before drawing hostile fire.

And like many other remote and rural parts of Afghanistan, the local population had begun souring on the American presence after airstrikes had hit civilians in the neighboring villages.

Deployment into Nuristan

The initial military goal was to establish the base as a one of 13 Provincial Reconstruction Teams set up throughout Afghanistan to help with reconstruction projects, civil affairs and basic safety for the local population. Within a year, the PRT had been moved to a safer, more hospitable base in the western section of the province.

Camp Keating, along with two other outposts near the border, was then intended to help patrol and oversee the stretch of the Pakistan border. U.S. officials were concerned that the nearby mountain passes were being used by militants to infiltrate Afghanistan and set up for attacks.

American officials were often divided over whether the U.S. effort in the mountainous region could be sustained.

According to an American who has consulted with U.S. forces on their deployment into Nuristan, the effort in the north can only be seen as a failure.

"What have we done there in the last three, four years," he said. "We didn't gain anything. We weren't able to open the road up or make the area secure.

Despite the inherent physical vulnerabilities of Camp Keating, until this weekend, the base had suffered no casualties from hostile fire. The base itself was named after Lieutenant Benjamin Keating, who was killed in vehicle accident nearby in Nov. 2006.

But on Saturday, a force of as many as 300 insurgents attacked the vulnerable base in what the military has termed a "complex" attack that began in a neighboring village mosque. According to an Afghan translator for American forces in Nuristan, the village mosque was used to store the weapons and ammunition used in the attack. The rules of engagement generally prevent U.S. forces from searching or attacking Afghan mosques.

According to the Afghan translator, most of the insurgents were local. Eastern Nuristan has long been filled by the insurgent group led by former mujahedeen leader Gulbuddin Hekmatyar, called Hezb-e-Islami. U.S. officials believe that Hekmatyar is hiding in Pakistan, and helps coordinate insurgent attacks throughout eastern Afghanistan.

Insurgent Attack

One U.S. military official told ABC News that they believe the insurgents started a fire as they began to attack. "They burned the base down," said the official.

The smoke from the fire initially limited the air support U.S. soldiers requested, according to a military official. The fighting lasted "throughout the day" as there were signs that the insurgents were able to breach the base before being "repelled." As insurgents fired from three or four different locations above the base, they also maneuvered and over took one of the observation posts on higher ground, taking out a post meant to protect Camp Keating from enemy fire.

The outpost at its peak was home to roughly 100 U.S. soldiers and a few dozen Afghans from both the national army and police force. According to reports, the base was down to half that size when the attack came over the weekend.

Patrols in the neighboring villages and mountaintops were often limited by the lack of U.S. forces, and forced commanding officers to stay on base for fear of being over-run while on patrol.

According to a senior state department official familiar with the area, the attack came as a surprise, and was "much bigger than anything U.S. forces could have expected."

The soldiers were preparing to leave the base for good this week, in a plan that had been set in motion as early as a year ago, according to American officials familiar with the military's plan. Military officials have said that they do not believe the insurgents knew the U.S. forces were withdrawing from the base.

The attack, according to a senior State department official, was most likely the last major effort by the insurgents before the winter snows blanket the province and make maneuvering and fighting that much harder to accomplish.

"Unfortunately," said the State Department official, "this [attack] gives the insurgents a propaganda victory because they can go and claim to the locals that they forced the Americans out."

With additional reporting by Nick Schifrin.