According to Rodriguez, among the factors military planners will use to identify forces to be drawn down will be the ability of local Afghan security forces to "plan and execute and lead operations."
"The real issue for when we can begin the drawdown is when they can accomplish the mission with less of us," he added. "And that less of us starts with infantry soldiers. And the longer-term enabling factors that I just talked about will be what we enable and support them for the foreseeable future."
Overall, Rodriguez said, the situation in Afghanistan is still "fragile and reversible," but it is "starting to get past that level in selected areas."
The drawdown will involve the thinning out of U.S. forces in a given area and redistributing them to areas where they are needed. Rodriguez said that would involve thinning out forces in southern Afghanistan and sending them to more volatile eastern Afghanistan.
Rodriguez said that the overall number of violent attacks in Afghanistan this year has gone up slightly, but at the same time he indicated that the number of effective Taliban attacks has gone down.
"As far as the violence levels, it's a mixture," he said. "Some of them are up a little bit; and in places where we focused our energy, they are down. It is a slight increase overall since last year."
One of those areas is eastern Afghanistan, but more IED's are being found in that region too.
While overall attacks have slightly increased, there was a significant increase in direct fire attacks, he said, but "they are very, very ineffective."
In the last six months 1,000 insurgents have been killed or captured, Rodriguez said. That's a 250 percent increase over the same time frame in 2010.