Strategypage explains the problem of arming locals:
To make this work in Afghanistan, the foreign troops, or the government, has to organize, and in some cases arm, the civilians. There are some special problems, however. The tribal situations are different in Iraq and Afghanistan, especially in the more urban areas. Afghanistan is mostly rural, with lots of villages, many in isolated valleys. People are very vulnerable to a large (a hundred or so armed men) group of Taliban. To the average Afghan, these guys are foreigners. In general, Afghans don't like foreigners, especially armed foreigners making threats. As the poorest country in Asia, with the shortest lifespan (44 years), Afghans don't like to take chances. If they see no way of dealing with the Taliban (or some local warlord, or drug gang), they will hunker down and make the best of it. ...
Americans have to make a convincing case that the Taliban will be taken care of (killed or hauled away to some distant jail.) This is why the U.S. wants to hand out weapons to some villagers, so they have a chance of holding off the Taliban.
As cell phone service spreads, the U.S. can give out prepaid cell phones, just as they earlier gave out pre-paid satellite phones. The U.S. can get reinforcements to any part of Afghanistan quickly. This does wonders in getting villagers to provide information on who the Taliban are, and what they are up to.
This is no theoretical concern, as an incident in the Tangi Valley demonstrates:
The area has seen few coalition forces for the past eight months after a small U.S. military team was brutally attacked and four were killed there last summer.
Shortly after the first few Soldiers with the 10th Mountain Division's 3rd Brigade Combat Team arrived here in February, they sent a little larger than a platoon-sized team into the valley. The troops were blasted by roadside bombs, rocket-propelled grenades and rifle fire. Remarkably, no one on the patrol was killed.
But, only days afterward, two local boys who had talked with coalition leadership during the mission were dragged from their homes and killed. It was a strong-arm attempt to strike fear into the local population, officials said, because the insurgents knew that with the growing U.S presence here, the coalition forces would be back.
It isn't enough for the locals to hate and fear the jihadis. The jihadis inspire those emotions naturally by their conduct. But for the locals to resist the jihadis, we have to make the case that we'll be around long enough to defeat the enemy jihadis. If we can't make that case, the locals will hunker down and cope with living in jihadistan rather than watch their boys hauled off and slaughtered.
As we commit to fighting in Afghanistan, I hope that President Obama remembers that by adding more troops we are promising the Afghans we will be around long enough to win.
Anything less is a betrayal of people who don't have the option of flying out and going home.