KABUL, Afghanistan — An Afghan Army soldier has shot dead three U.S. soldiers in the eastern part of the war-torn country, the NATO coalition said on Saturday.
So-called "insider attacks", in which Afghan forces turn their guns on their international partners, have killed scores of foreign troops in Afghanistan, breeding fierce mistrust and threatening to derail the training of local forces to take over security duties ahead of NATO's withdrawal next year.
"Three International Security Assistance Force (ISAF) service members died when an individual wearing an Afghan National Security Forces uniform shot them in eastern Afghanistan today," an ISAF statement said, adding that both ISAF and Afghan officials were investigating the incident.
A U.S. defense official confirmed to AFP that the three victims were from the United Sates.
An Afghan official, speaking on condition of anonymity, told AFP that the incident happened during a training session in the insurgency-hit eastern province of Paktia.
An Afghan National Army (ANA) soldier opened fire on US soldiers in a military training camp, killing two on the spot, he said. A third later died of his wounds, he added.
The attacker was killed when Americans and Afghan soldiers returned fire, he said.
The threat of "insider attacks" has become so serious that foreign soldiers working with Afghan forces are regularly watched over by so-called "guardian angel" troops to provide protection from their supposed allies.
ISAF officials say that most insider attacks stem from personal grudges and cultural misunderstandings rather than Taliban insurgent plots.
Afghan soldiers and police are taking on responsibility for battling the militants from 87,000 NATO combat troops who will leave by the end of 2014 — 13 years after a U.S.-led invasion brought down the Taliban regime.
But the 350,000-strong security forces are suffering a steep rise in casualties as the NATO combat mission winds down and Afghan authorities try to bring stability ahead of the presidential poll set for April next year.
On Friday Afghanistan's interior ministry confirmed that 18 policemen had been killed in a Taliban ambush in the northeastern province of Badakhshan.
The policemen, who were returning from an anti-insurgent operation in the town of Warduj, were ambushed by scores of armed militants resulting in a fierce firefight in which 18 officers were killed and 13 others injured, the interior ministry said in a statement.
The attack and casualties will heighten concerns that Afghan forces cannot provide effective security across the country, where a U.S.-led invasion ousted the hardline Taliban regime in 2001, in time for the presidential election due in April.
Also on Saturday Pakistan said it had released from prison Abdul Ghani Baradar, who is often described as the former second-in-command, and the most high profile Taliban commander detained in Pakistan.
The Afghan government, which has long called on Islamabad to free Baradar, hopes that the release will have a positive effect on peace efforts. Kabul hopes Baradar, who is described by many Afghan officials as more favored towards peace, will help facilitate Afghan government talks with the Taliban.
"Baradar is someone who has always been eager to join peace negotiations, and we hope he joins peace talks soon. We are optimistic about it, he is still an influential figure, and the Taliban still respect him." Mohammad Esmail Qasimyar, senior member of Afghan High Peace Council, told AFP.
Baradar's release brings to 34 the number of Taliban detainees that Pakistan has freed since last year, in what Afghan officials hope will encourage peace talks with the insurgents.
But analysts say that there is little evidence that the release of any of the Taliban detainees has had a positive effect on peace efforts, and several are understood to have returned to the battlefield.
Political analyst Talat Masood said the announcement was a "sort of a confidence-building measure between Pakistan and Afghanistan."
"However, this release is not likely to make any significant difference in the negotiating process," he said.