"I think the view of most of us is that until the momentum of the battle turns against the Taliban... that the likelihood of any kind of reconciliation on the part of the leadership of the Taliban is very small," Gates said.
Asked about a New York Times report that Taliban factions were in talks with the Kabul government and pushing for a deadline for the withdrawal of NATO-led forces, Gates said Washington would "absolutely not" accept any such idea.
The defense secretary said "the end of all such wars involves some measure of reconciliation. We've seen it in Iraq."
"And so the real issue is, will these guys reconcile on the terms of the Afghan government, or are they dictating terms to the Afghan government?"
The Taliban and associated insurgents in Afghanistan have stepped up violent attacks in the past two years despite the presence of 70,000 foreign troops.
President Barack Obama has approved the deployment of more than 21,000 additional US troops to Afghanistan to try to stem the rising violence, especially in the volatile south.
By the end of the year, US officials say the US force will reach 68,000.
The Taliban were ousted in 2001 in a US-led invasion which sent many of its fighters into Pakistan.
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