The U.S. military trainers handed the new recruit, Mohammad Ismail, his AK-47 to defend his remote Afghan village. He turned around and immediately used it, spraying the Americans with bullets and killing two — the latest of nine U.S. service personnel gunned down in two weeks by their supposed Afghan allies.

The shooting in western Farah province was not the only such attack Friday. Hours later a few provinces away in Kandahar, an Afghan soldier wounded two more coalition servicemen.

One turncoat attack per month raised eyebrows last year. One per week caused concern earlier this year. But when Afghan forces turn their guns on international trainers twice in a day — as they now have two weeks in a row — it's hard to argue there's not something going on. The question is, what is it?

The U.S.-led alliance says it's too soon to tell what's behind the rash of insider attacks. The most likely explanations: Either the Taliban are increasingly infiltrating the Afghan police and army, or relations between Afghan and American forces are turning toxic — or both.

"There's no positive spin on this," said Andrew Exum, an analyst with the Washington-based Center for a New American Security who has advised the top U.S. generals in Kabul. He said the number of Afghan insider attacks has risen beyond what can be explained as isolated incidents.

That's bad news for the U.S. exit strategy for Afghanistan, which has seen Washington spend more than $20 billion on training and equipping a nearly 340,000-member Afghan security force on the assumption that it would eventually be strong enough to fight the Taliban on its own.

The coalition has downplayed the insider attacks as anomalies and mostly a result of personal grievances, even as their numbers soared from 11 last year to 29 so far in 2012. The alliance says only about 10 percent of the attacks were related to infiltration by the Taliban insurgency. But that analysis was done before the latest furious spate of seven attacks in 11 days, a frequency that suggests some type of coordination.

"Whether or not these specific events turn out to be insurgent-initiated ... we're just going to have to do the investigations and figure that out," said Jamie Graybeal, a spokesman for the U.S.-led coalition.

The problem has become so pronounced in the Afghan war that all U.S. forces there are now being instructed to carry loaded weapons — even on base — as a precaution against insider attacks, a U.S. official said Friday in Washington. The official spoke on condition of anonymity because policy forbids discussing military procedures.

Some historians are hard-pressed to find precedent for this in previous wars.

"I have never heard of anything in Vietnam comparable to what we have recently experienced in Afghanistan," said James McAllister, a political science professor at Williams College in Massachusetts who has written extensively about the Vietnam War. A British military expert on colonial wars, Martin Windrow, said the level of these types of attacks were "almost unheard of" in any conflict he'd studied.

Exum said the insider attacks have "tremendous strategic impact" beyond the 36 coalition forces killed this year because they damage morale among international troops and further weaken support for the war in the U.S. and other NATO nations training Afghan soldiers and police to take over security nationwide by 2014.

What's unclear, he added, is how much influence the Taliban actually have in organizing the increasing numbers of attacks.

The insurgents have been happy to take credit. The Taliban's supreme leader, Mullah Mohammad Omar, boasted Thursday that the insurgents "have cleverly infiltrated into the ranks of the enemy" and were killing a rising number of U.S.-led coalition forces.

Defense Secretary Leon Panetta told The Associated Press in an interview this week that the attacks may reflect the Taliban's use of unconventional tactics against a coalition force it cannot defeat on the battlefield. He added that U.S. military commanders say such attacks still remain "sporadic" and not a long-term trend.

Friday's deadly shooting in Farah, at least by the accounts of local Afghan officials, seemed unlikely to be a personal dispute. Mohammad Ismail, a man in his 30s, had joined the Afghan Local Police just five days earlier. He opened fire during an inauguration ceremony attended by American and Afghan forces in Kinisk village, Farah provincial police chief Agha Noor Kemtoz said.

"As soon as they gave the weapon to Ismail to begin training, he took the gun and opened fire toward the U.S. soldiers," Kemtoz said. The police chief added that he had warned U.S. forces organizing and training the community not to move too fast to recruit in the village, which he said is heavily influenced by the Taliban.

Afghan military analyst Amrullah Amman has no doubt that Taliban infiltration of Afghan security forces is rising. He said that despite new methods of screening, it's simple to forge documents and invent references in Afghanistan.

"The gate is wide open. The enemy is infiltrating because they see it's very easy," Amman said.

But the turncoat attacks may also reflect growing mistrust and resentment among Afghans working with international forces.

Afghan soldiers interviewed by the AP earlier this year offered their own explanations: The Afghans feel disrespected, the soldiers said. They complained of getting inferior equipment and condescending treatment by Americans.

In May 2011, a U.S. Army team led by a behavioral scientist compiled a survey that indicated many Afghan security personnel found U.S. troops "extremely arrogant, bullying and unwilling to listen to their advice."

"I think infiltration is easier to address, actually," Exum said. "I think the worse thing is, if your entire strategy going forward from the next three or four years depends on partnering with Afghan forces, then if relations have already devolved to this degree, you're really worried."

The U.N. Security Council late Friday strongly condemned coordinated terrorist attacks in various parts of the country on Tuesday and Wednesday and reiterated its serious concern "at threats posed by the Taliban, al-Qaida and illegal armed groups to the local population, national security forces, international military and international assistance efforts in Afghanistan."


Associated Press writers Amir Shah in Kabul, Robert Burns in Washington, Slobodan Lekic in Brussels and Edith Lederer at the United Nations contributed to this report.