Vows of revenge by the Taliban against U.S.-led forces in Afghanistan have raised anxieties for Western personnel in the region in the wake of a weekend massacre of 16 civilians by an American soldier.
The Sunday shooting spree, which further inflamed already fraught relations between locals and foreign troops, elicited calls on Monday by politicians in Afghanistan's parliament for a public trial for the U.S. attacker.
In a statement to the families of the victims, the Taliban pledged militants would avenge "every single martyr with the help of Allah."
The promise of retaliatory violence against U.S.-led forces in Afghanistan put the U.S. Embassy on high alert as American residents in Kabul elected to remain in their homes due to fears of reprisals.
"There's a wait-and-see attitude," freelance reporter Jennifer Glasse told CBC News from Kabul, adding that U.S. forces and the International Security and Assistance Force (ISAF) are watching the next two days with apprehension.
"All eyes really are on Kandahar, the southern city, where a prayer service tomorrow will be held at a main mosque. That will be really what everyone will be watching," Glasse reported.
She said elders in Kandahar had said there would be no attacks against U.S.-led forces, so long as they are satisfied the perpetrators behind Sunday's killings of mostly women and children are brought to justice.
U.S. officials said the suspected shooter, who turned himself in at his base, will be tried under U.S. law, indicating he won't be handed over to Afghan authorities.
Burning of Qur'ans led to initial violence
Frayed tensions in Afghanistan over the accidental burnings of Qur'ans at a U.S. army base quickly descended into bloody conflict last month. The Taliban claimed responsibility for several attacks, saying the desecration of the Islamic holy text by Americans warranted the violent reaction.
Afghan forces also turned their guns on their supposed allies, killing six U.S. troops as violent protests racked the country. The weeks of violent protests and attacks also left some 30 Afghans dead, despite an apology from U.S. President Barack Obama.
Sunday's shootings will likely spark even greater distrust between Washington and Kabul and fuel questions in both countries about why American troops are still fighting in Afghanistan after 10 years of conflict and the killing of Osama bin Laden.
Glasse told CBC News that NATO officials had expressed concern that the wave of killings jeopardizes the NATO mission in Afghanistan.
"It's all about trust, it's all about transition," she said. "We're at a stage where American and NATO forces are handing over control to the Afghan security forces, and they're trying to have the Afghan security forces win the trust of the Afghan people in terms of safety and security."
Clinton insists killings won't change diplomatic mission
Speaking at the UN on Monday, U.S. Secretary of State Hillary Clinton told reporters she was "shocked and saddened by the killings of innocent Afghan villagers" and sent her condolences to the victims' families.
"This not who we are," she said. "And the United States is committed to seeing that those responsible are held accountable."
Clinton said it was "obvious to everyone" that the past few weeks have been difficult in Afghanistan, but that the incident must not derail diplomacy there.
"This terrible incident does not change our steadfast dedication to protecting the Afghan people and to doing everything we can to help build a strong and stable Afghanistan," she said.
With that in mind, Clinton said, the U.S. recognizes "that an incident like this is inexplicable and will certainly cause many questions to be asked."
Kate Clark, a senior analyst with the Afghanistan Analysts Network, told CBC News from Kabul on Monday that a "grim atmosphere" could be felt on the ground there, as word of the massacre in two villages continues to spread.
"Either people are hearing about it on the radio or seeing the images on TV," she said. "We've had the Taliban vowing revenge, we've had [Afghan President Hamid] Karzai saying this was an assassination and forgiveness is impossible. We've had the Afghan parliament also calling for justice."
Taliban condemn 'sick-minded American savages'
The Taliban said in a statement on their website that "sick-minded American savages" committed the "blood-soaked and inhumane crime" in two villages in Panjwaii district, a rural region outside Kandahar that is the cradle of the Taliban and where coalition forces have fought for control for years.
As yet, there has not been much action on the streets, Clark reported, as demonstrations in Afghanistan are usually organized.
The suspected shooter's name has not been released, but reports say he is a 38-year-old army staff sergeant who has served three tours of duty in Iraq and arrived three months ago in Afghanistan for his first tour there. ABC News reported the man is a married father with two children, citing a U.S. army official, who spoke on condition of anonymity because the investigation is ongoing.
The shooting suspect was deployed to Afghanistan on Dec. 3 with the 2nd Battalion, 3rd Infantry Regiment of the 3rd Stryker Brigade, 2nd Infantry Division, based at Joint Base Lewis-McChord located south of Seattle, a congressional source told The Associated Press. He was assigned to help support a village stability operation in Belambai, about a kilometre away from one of the villages where the attack took place. Special operations troops pair with local residents chosen by village elders to become essentially a sanctioned, armed neighborhood watch.
The wire service cited an anonymous congressional source, whose name was withheld due to the sensitivity of the situation.
He is being held in pretrial confinement in Kandahar by the U.S. military while army officials review his complete deployment and medical history, according to the source.
The killings were a blow to the community at Joint Base Lewis-McChord in Washington, a base which has seen its share of controversies and violence in the past few years.
Four Lewis-McChord soldiers were convicted in the deliberate thrill killings of three Afghan civilians in 2010. The base, home to about 100,000 military and civilian personnel, has also had a spate of suicides among soldiers back from war.
The spokesman for the NATO-led coalition in Afghanistan, Brig.-Gen. Carsten Jacobson, said ISAF was "shocked and saddened" to hear of the killings.
"ISAF offers its profound regret and deepest condolences to the victims and their families," Jacobson said.
The U.S. military has said there is no indication that more than one soldier carried out the attacks in two villages in Kandahar province before dawn Sunday. But villagers told Afghan officials they heard shots being fired from several directions.
Some Afghans doubt shooter acted alone
Afghans have expressed doubt that a single soldier could have carried out the 3 a.m. door-to-door shootings in the villages of Balandi and Alkozai, which lie some two kilometres apart. Most of the victims were women and children who were shot as they slept.
Villagers said the gunman entered at least three homes and that nine of the victims were children. Some of the bodies were also set on fire.
"One man can't kill so many people. There must have been many people involved," Bacha Agha of Balandi village told The Associated Press. "If the government says this is just one person's act we will not accept it.… After killing those people they also burned the bodies."
In a statement, Karzai also left open the possibility of more than one shooter, referring to "American forces" entering Afghan houses.
"This is an assassination, an intentional killing of innocent civilians and cannot be forgiven," Karzai said.
Obama calls shootings 'tragic and shocking'
Such operations are among NATO's best hopes for transitioning out of Afghanistan, pairing special operations troops with villagers chosen by village elders to become essentially a sanctioned, armed neighbourhood watch.
Obama and U.S. Defence Secretary Leon Panetta called Karzai on Sunday to express their shock and sadness, and to offer condolences to the grieving families and the people of Afghanistan.
In a statement released by the White House, Obama called the attack "tragic and shocking" and not representative of "the exceptional character of our military and the respect that the United States has for the people of Afghanistan." He vowed "to get the facts as quickly as possible and to hold accountable anyone responsible."
Despite the slayings, American diplomats said they hope Americans and Afghans can continue to work together peacefully toward stabilizing the region.
"We are committed to an enduring relationship with Afghanistan, to attain greater peace and security in the region, which is our common interest," said James Cunningham, acting U.S. ambassador to Afghanistan.
Obama said at a recent White House press briefing that violent protests spurred by the Qur'an burnings underscored the need to enact a faster exit strategy, telling reporters "now is the time for us to transition." Although questions remain over whether that means a withdrawal of U.S. forces will happen before the 2014 deadline to hand over security, Obama has said there are no such plans to change the scheduled pullout timetable.