Last updated 2:25 p.m. Eastern
The CIA said Thursday that seven of its employees were killed and six others wounded in a suicide bombing at a base in Afghanistan. The Associated Press has learned that one of them was the chief of the CIA's post in Afghanistan's southeastern Khost Province.
The CBSNews.com Special Report: AfghanistanNo further information about the victims would be released," the CIA director said, "due to the sensitivity of their mission and other ongoing operations."President Barack Obama said the killed CIA employees come from a "long line of patriots" whose courageous service has helped to thwart terrorist plots and save lives.
In a letter to CIA employees released by the agency, Mr. Obama said the U.S. would not be able to maintain its freedom and security without their service. He also noted that the spy agency has been tested "as never before" since the Sept. 11 attacks.
The president, who is in Hawaii for the holidays, wrote to tell them they "have helped us understand the world as it is, and taken great risks to protect our country."
Separately, former CIA officials said an agent who ran the agency's base in Khost was among those killed by the attacker, who detonated a bomb-laden vest inside the compound.
The former officials said the Khost chief was the mother of three. As base chief she would have directed and coordinated CIA operations and intelligence gathering in the province, a hotbed of Taliban and insurgent activity because of its proximity to Pakistan's lawless tribal region.
The former officials spoke on condition of anonymity because they were not authorized to speak publicly.
CBS News correspondent David Martin reports Afghan soldiers and civilians are present at almost every American outpost since one of the chief principals of the U.S. strategy is to partner with the Afghans. According to Christine Fair of Georgetown University, some of them may actually be.
"They have really become a vehicle of infiltration for the Taliban," Fair said. "This is most certainly a vulnerability in our strategy going forward in trying to hand over security to the Afghans," said Fair; "If we don't really have a way of figuring out who we can trust."
An Afghan official in Khost said about 200 Afghans have been contracted by the U.S. to take care of security at the base. They are usually deployed on the outer ring of its walls, although some work inside, the official said on condition of anonymity because of the sensitivity of the issue.
"It's not the first time that Afghan forces have conducted such an attack to kill Americans or foreigners," the Taliban statement said, citing the killing of an American soldier and the wounding of two Italians this week in Badghis province. NATO has provided no details of that incident, but Afghan Gen. Jalander Shah Bahnam said an Afghan soldier opened fire on a base in the province's Bala Murghab district.
Separately, four Canadian soldiers and a journalist embedded in their unit were killed Wednesday by a roadside bomb in Afghanistan's south, the bloodiest single incident suffered by that country's military in 2009.
Michelle Lang, a 34-year-old health reporter with the Calgary Herald, was the first Canadian journalist to die in Afghanistan. She arrived in the country just two weeks ago.
Asked about the suicide attack, NATO said only that FOB Chapman, in Khost, is used by provincial reconstruction teams, which consist of both soldiers and civilians, and other personnel.
A spokesman in Kabul for the international coalition force said no U.S. or NATO troops were killed in the afternoon explosion. The attack was the bloodiest for Americans since eight soldiers were killed in an insurgenton Oct. 3.
In the south, NATO said the four Canadian troops and the reporter died when their armored vehicle hit a bomb while on an afternoon patrol south of Kandahar city. It was the third-deadliest day for Canadians in Afghanistan since the war began.
Michelle Lang "was one of those journalists who always wanted to get to the bottom of every story so this was an important trip for her," said a Calgary Herald colleague, Colette Derworiz.
The military has not disclosed the names of the Canadian troops because relatives have not all been notified.
"We are all very saddened to hear this tragic news," Alberta Health and Wellness Minister Ron Liepert said in a statement. "Michelle covered health issues with professionalism, accuracy and thoroughness. She was tenacious in her quest to inform Albertans, and for her diligence she was very well respected."
Brig. Gen. Daniel Menard, commander of coalition forces in Kandahar, said the soldiers were conducting a community security patrol in order to gather information about daily life in the area and how to maintain security.
Separately Wednesday, NATO questioned Afghan reports that international troops killed 10 civilians, including children, in a weekend attack that prompted hundreds of angry Afghan protesters to burn an effigy of President Obama and chant "death" to America.
The head of an investigative team appointed by President Hamid Karzai told The Associated Press that eight students between the ages of 12 and 14 were among the dead discovered in a village house in a remote section of Kunar province in eastern Afghanistan. NATO said late Wednesday that while there was no direct evidence to substantiate the claims, the international force had requested and welcomed a joint investigation to reach an "impartial and accurate determination" of what happened in the attack.
Conflicting accounts of what occurred during the fighting in Kunar's Narang district prompted an emotional outcry over civilian deaths, one of the most sensitive issues for international troops fighting the more than eight-year-old war. Although insurgents are responsible for the deaths of far more civilians, those blamed on coalition forces spark the most resentment and undermine the fight against militants. With 37,000 more U.S. and NATO troops being deployed to the battle zone, concern over civilian casualties is unlikely to ease anytime soon.
Several hundred Afghans demonstrated in Kabul and in the eastern city of Jalalabad, where the likeness of Obama, adorned with a small American flag, was burned on a pole held above demonstrators.