KABUL, Afghanistan -- A wave of betrayal has left at least 17 Afghan policemen dead in the past 10 days -- all killed in their sleep, at the hands of those close to them.
Early Thursday morning, an Afghan policeman unlocked the door of the check post where he was stationed in Oruzgan Province and let in his friends from the Taliban, who helped him attack his sleeping colleagues with knives and guns, eventually killing four and wounding eight.
On Sunday, a local police commander in a remote northern province, Jawzjan, shot to death, in their beds, five men under his command and fled to join the Taliban.
And on Dec. 18, a teenager apparently being kept for sexual purposes by an Afghan border police commander in southern Kandahar Province drugged the commander and the other 10 policemen at the post to put them to sleep, and then shot them all; eight died.
In the crisis that has risen in the past year over insider killings, in which Afghan security forces turn on their allies, the toll has been even heavier for the Afghans themselves -- at least 86 in a count by The New York Times this year, and the full toll is likely to be higher -- than it has been for American and other NATO forces, which have lost at least 62 so far, the latest in Kabul on Monday.
Unlike most insider attacks against foreign forces, known as "green-on-blue" killings, most of the attacks between Afghans, "green on green," have been clear cases of either infiltration by Taliban insurgents or turncoat attacks. As with the three recent attacks, they have fallen most heavily on police units, and they have followed a familiar pattern: the Taliban either infiltrate someone into a unit, or win over someone already in a unit, who then kills his comrades in their sleep. Frequently, the victims are first poisoned or drugged at dinner.
"I tell my cook not to allow any police officer in the kitchen," said Taaj Mohammad, a commander of a border police check post near the one in Kandahar that was attacked on Dec. 18. "This kind of incident really creates mistrust among comrades, which is not good. Now we don't trust anyone, even those who spent years in the post."
The most recent of the green-on-green betrayals took place on Thursday about 3 a.m., in the town of Tarin Kowt, the capital of Oruzgan Province in southern Afghanistan. According to Fareed Ayal, a spokesman for the provincial police chief, a police officer named Hayat Khan, who had been in regular touch with the Taliban for religious guidance, waited until the other officers at his check post fell asleep and then called Taliban fighters by cellphone and let them in. First the attackers stabbed the one officer who was on watch, but he raised the alarm in time to awaken some of the police officers.
In the ensuing firefight, four policemen were killed and eight wounded, while Mr. Khan and his Taliban confederates managed to escape, according to Mr. Ayal's account.
In the attack on Sunday, in Jawzjan Province, the victims were all part of an Afghan Local Police unit whose commander had previous connections with the Taliban. Such local police units, strongly supported as part of American policy in Afghanistan, undergo training, and community leaders and elders offer guarantees that the units have no further insurgent ties.
Gen. Abdul Aziz Ghairat of the Jawzjan Provincial Police said that the commander who had killed the men in their sleep, Dur Mohammad, had fled but that his relatives and a community elder who vouched for him had been detained and were being interrogated.
In some green-on-green cases, personal grievances may drive the attackers to throw in their lot with the Taliban.
That is apparently what happened in the case of Noor Agha, a young man who the police say killed eight border security police officers in their check post on the border near Spinbaldak, the major crossing point between Kandahar and Pakistan, on Dec. 18.
The police said that Mr. Agha, whose age was unclear but whom police sources described as "still beardless," had been the involuntary companion of the border police commander at that check post, Agha Amire, for several years. Other police commanders who knew both said there was clearly an "improper relationship" between the two.
While not saying so explicitly, they were suggesting that Mr. Amire was using Mr. Agha in the commonplace practice known as bacha baazi, in which powerful Afghan commanders frequently keep young boys as personal servants, dancers and sex slaves.
The practice was outlawed during Taliban times but has never gone away, and even some provincial governors and other top officials openly keep bacha baazi harems. The practice was noted in the latest United States State Department's annual human rights report, but the report said "credible statistics were difficult to acquire as the subject was a source of shame."
The night of the attack, Mr. Agha offered to make a special dinner for the police at the check post and invited two friends to attend. He and his friends put drugs in the food and then shot everyone there, including Mr. Amire, and the three attackers escaped across the border to join Taliban insurgents in Pakistan, according to a police official. Mr. Agha's family, who lived in Arghandab District, a former Taliban stronghold near Kandahar city, fled their home, leaving behind livestock and personal possessions, according to police officials and relatives of the commander.
Although a police official who spoke on the condition of anonymity put the toll at eight dead and three wounded in that episode, officially, the Kandahar Province police chief, Gen. Abdul Raziq, said only four had been killed and three wounded. General Raziq also denied that there had been a young boy involved in drugging the food.
The wave of killings over the past year has police officers all over Afghanistan watching what they eat, and sleeping uneasily.
"We make sure that nobody gets the chance to poison the food," said Sharif Agha, 26, a police sergeant who commands a small outpost in Khost city, in eastern Afghanistan. The ten officers there take turns helping the cook and make sure at least two people are in the kitchen at all times. At night, a third guard is assigned to watch the two guards normally on duty.
"I don't know about the rest of the guys," Sergeant Agha said, "but I have not slept properly over the past few months."
Reporting was contributed by Taimoor Shah from Kandahar, Afghanistan; Habib Zahori and Jawad Sukhanyar from Kabul; and Enayat Najafizada from Mazar-i-Sharif.
This article originally appeared in The New York Times.