Washington (CNN) -- While the Obama administration plans to review its Afghanistan strategy in December and wants to begin withdrawing troops next July, it won't have a clear picture of progress in a key offensive in the south until just before that deadline, the commander in charge of the southern region said Thursday.
The United States and its allies launched a major offensive this summer in the Taliban stronghold of Kandahar. British Army Brig. Gen. Nick Carter, who commands NATO troops in southern Afghanistan, pointed to what he called "some encouraging signs, definitely momentum and a sense probably that the initiative is now with us and not -- as it was a year ago -- with the insurgency."
He said final evaluation must wait.
"In Afghanistan you have to be very careful about not measuring progress until you match it to the appropriate season and the appropriate time of year. And I sense it won't be until June next year that we'll be sure that the advances we've made in the course of the past few years are a genuine success," Carter said.
"You just need to look forward to June next year I sense, to be sure these positive trends are definitely banked and are being successful," Carter said in a video question-and-answer session from Afghanistan with journalists at the Pentagon.
He said for economic reasons many young men spend April and May on the poppy harvest and then the wheat harvest.
"What then happens from ... June onwards is that the canopy begins to come out on the trees, the vegetation grows up and you get quite a lot of quite complex terrain and cover which gives the insurgents confidence to operate against their security forces, in a way that they don't have that confidence in the months of December, January and March when the vegetation dies off and it becomes very easy to see people moving," Carter said.
A variety of trends suggest some improvement already, including better freedom of movement, safer travel, elders returning to villages and people coming forward to volunteer information about weapons caches or improvised explosive devices, Carter said..
But he said he also relied on anecdotal information, such as greater "exuberance" in celebrations at the end of Ramadan, the Muslim holy period of prayer and fasting, and even talks with his local barber.
"First question I always ask him during my haircut is how are the Afghan national police treating him this week. And each week he tells me they are treating him better. Now, that is anecdotal but it is those sort of things that give you a sense whether this thing is moving in the right direction or not."
He said new recruits were joining the Afghanistan army and training courses for the Afghan police were full.
"The key challenge is to grow that Afghan capacity so that we can begin to turn our attention to other requirements and allow those Afghan security forces to step up to the plate and own the problem," Carter said.