Two of the biggest goals for U.S. forces in Afghanistan are building up Afghan security forces and convincing Taliban members to lay down their arms. It seems some of both goals can be accomplished with some cash.

Defense Secretary Robert Gates, who arrived for an unannounced trip to Afghanistan on Tuesday, said money is a key reason why the Afghans might be having recruiting and retention problems with its security forces.

"One of the eye openers for us was learning that the Taliban, for the most part, are better paid than the Afghan Security Forces, so that's something that we and the Afghans have already taken steps to correct," the DOD chief said. "They're raising the pay of the police and they're putting in place a number of additional incentives and bonuses and so on for the army in terms of combat pay and various things like that so that clearly will help. I think, frankly, that's the biggest obstacle."

So how much money do you get if you fight for the Taliban?

Around $300, according to Gen. Stanley McChrystal, the senior NATO and U.S. forces commander in Afghanistan.

"There is no set pay scale, but by our intelligence, they are paying the equivalent of about $300 a month and that is higher than we are paying Afghan army or police," McChrystal told the Senate Armed Services Committee, where he testified on Tuesday.

So the U.S. is minding the gap, if you will, and along with the Afghan government, raising the pay for Afghan troops. (Watch inside the Afghan recruitment process from CNN's Atia Abawi)

"In coordination with the Afghan government, we just almost doubled Afghan army and police training [pay]. It is in parity now. It is less than $300 a month but it's much closer," he told the committee.

"Almost doubling" indicates prior pay was in the neighborhood of $150 a month. It's no surprise then that the Afghan Security Forces have suffered from corruption charges and desertion– especially in the face of higher Taliban pay.

The higher pay could also help encourage lower level Taliban to instead lay down their weapons and perhaps join Afghan security forces.

"Obviously, you have to make it more attractive for individuals to serve on the side of the government rather than take up with the Taliban. Wages have to encourage," said Pentagon spokesman Bryan Whitman.

Neither the Afghan government nor ISAF pays fighters to come off the field, according to an official with the International Security Assistance Force (ISAF) office who spoke to the Afghanistan Crossroads blog on background.

And the ISAF official explained that if fighters choose to turn themselves over to the Afghan National Security Forces, their government will try to give them jobs. The official reiterated that "it's all Afghan-led."

The U.S. and Afghanistan are looking to increase the Afghan security force of police and military to 300,000 strong by July 2011 from its current level of approximately 190,000. But Afghanistan, with its struggling economy, will need help to pay for that force with U.S. and international assistance for the next 10 to 15 years, President Hamid Karzai said Tuesday.

"Afghanistan will not be able to sustain a force of that nature and capability with its own resources." Karzai said.

Related: McChrystal before Congress

Related: Barbara Starr on Gates in Afghanistan