A newly recruited Afghan village policeman opened fire on his American allies on Friday, killing two U.S. service members minutes after they handed him his official weapon in an inauguration ceremony.
It was the latest in a disturbing string of attacks by Afghan security forces on the international troops training them.
Later on Friday, an Afghan soldier turned his gun on foreign troops in another part of the country and wounded two of them, a spokesman for the NATO coalition said.
The attacks in the country's far west and south brought to seven the number of times that a member of the Afghan security forces - or someone wearing their uniform - has opened fire on international forces in the past two weeks.
Such assaults by allies, virtually unheard of just a few years ago, have recently escalated, killing at least 36 foreign troops so far this year. They also raise questions about the strategy to train Afghan national police and soldiers to take over security and fight insurgents after most foreign troops leave the country by the end of 2014.
The NATO-led coalition has said such attacks are anomalies stemming from personal disputes, but the supreme leader of the Taliban boasted on Thursday night that the insurgents are infiltrating the quickly expanding Afghan forces.
Friday's deadly attacker in the far western province of Farah was identified as Mohammad Ismail, a man in his 30s who had joined the Afghan Local Police just five days ago.
He opened fire during an inauguration ceremony attended by American and Afghan forces in the Kinisk village, the Farah provincial police chief Agha Noor Kemtoz said.
"As soon as they gave the weapon to Ismail to begin training, suddenly he took the gun and opened fire toward the U.S. soldiers," Kemtoz said.
Ismail was shot and killed as the coalition and Afghan forces returned fire, the police chief said.
A spokesman for the international coalition force, Jamie Graybeal, confirmed that two American service members were killed on Friday by a member of the Afghan Local Police.
The ALP is different from the national police and represents a village defense force under the Ministry of Interior that is being trained by international forces, including U.S. special forces.
Graybeal gave no other details on the Farah attack other than confirming the shooter had been killed.
Kemtoz, the police chief, said the attack took place about 8 a.m., after the U.S. forces arrived in the village to train the local police. He said one Afghan National Police officer was also seriously wounded in the shooting.
Later on Friday, an Afghan army soldier fired on coalition troops in the southern province of Kandahar. Two of the international troops were wounded but none was killed in that shooting, Graybeal said. He added that the soldier was shot and died later on Friday of his wounds.
So far in 2012, there have been 29 attacks reported on foreign troops by Afghans they are training, compared to 11 attacks in 2011, according to an Associated Press count, and five attacks in each of the previous two years.
Seven such attacks have come in the past two weeks alone, with six American troops killed last on Friday in two separate shootings in Helmand province in the south and another American killed a few days previously on a U.S. base in Paktia province in the east.
The trend raises questions about potential resentment by Afghans after more than a decade of international presence since the American-led intervention to oust the Taliban regime from power for harboring the al-Qaida terrorist leadership after the Sept. 11, 2001 attacks in the U.S. The insider attacks also renew concern that insurgents may be infiltrating the Afghan army and police, despite intensified screening.
Insurgent infiltration or recruitment was behind only about 10 per cent of this year's reported attacks on coalition forces by Afghan allies, Graybeal said earlier this week, citing investigations into attacks before those of the past week.
Graybeal insisted the deadly violence is relatively small scale compared to the nearly 340,000 Afghan security forces now being trained.
The international coalition has said that Afghan forces are increasingly able to lead operations and already have started to assume responsibility for security in areas of the country that are home to 75 percent of the Afghan population.
However, the Taliban have been quick to seize on the increasing number of attacks as a sign of Afghan rejection of foreign forces and the insurgents' own successful recruitment.
The group's supreme leader Mullah Mohammad Omar said Thursday night that the insurgents 'have cleverly infiltrated in the ranks of the enemy' and were successfully killing a rising number of U.S.-led coalition forces.
In an email to media organizations, Omar said the plan to transfer responsibility to Afghan forces by the end of 2014 is a 'deceiving drama' that the international community has orchestrated to hide its defeat.
The Taliban leader's message came on the same day that a U.S. military helicopter crashed during a firefight with insurgents in a remote area of southern Afghanistan, killing seven Americans and four Afghans in one of the deadliest air disasters of a war now into its second decade.