"They're able to put something like 25,000 fighters into the field," said Ahmed Rashid.
Rashid, a best-selling author and journalist, paints a bleak picture of a resilient Taliban force, deep ethnic divides among Afghans, and an economy that could collapse if U.S. forces leave. He also makes comparisons to Vietnam.
"I think any guerilla force that is able to maintain sanctuaries and safe havens in a neighboring country, really cannot be defeated," said Rashid.
But Rashid believes the U.S. can have success by the time U.S. troops are scheduled to leave in 2014.
"If you want to end this war before you leave, you have to make an attempt at reconciling the Taliban with the Karzai government," said Rashid.
Despite recent atrocities by U.S. soldiers on the Afghan population, Rashid believes the Taliban still wants to negotiate a possible power-sharing deal. He says the 10-year conflict has depleted their resources and morale is low.
"They're fed up with Pakistan and the manipulation that they have been under by the Pakistani intelligence," said Rashid.
However, Rashid says Al Qaeda would be determined to sabotage any negotiations. He speaks again at another free lecture this Thursday at the UC Berkeley Art Museum at 7 p.m.