U.S. Defence Secretary Jim Mattis arrived in Kabul in an unannounced visit, Tom Gresback, the spokesman of U.S. and NATO's Resolute Support mission in Afghanistan, told newsmen.
The Taliban has said it will talk to the United States, but not the Western-backed Afghan government the insurgents see as illegitimate.
Mattis said we shouldn't expect peace moves from the Taliban en masse, but that some might be open to talks.
Mattis said he's seen initial indications that there have been changes in Pakistan's behavior but that he wants to use the trip to find out more.
He said: "Right now, we want the Afghans to lead, and provide the substance of the reconciliation effort".
He flew into the war-torn city two weeks after Afghan President Ashraf Ghani unveiled a plan to open peace talks with the Taliban.
The US has a renewed focus on Afghanistan after years of drawdowns under former US president Barack Obama, and talk by top US generals of "not winning" and a "stalemate" in the seemingly intractable conflict.
"It has been a game-changer because it has forced every actor to re-examine their assumptions", he said.
Western diplomats and officials in Kabul say contacts involving intermediaries have been underway with the aim of agreeing on ground rules and potential areas of discussion for possible talks with at least some elements in the Taliban.
However, the insurgents, who seized a district center in western Afghanistan earlier this week, have given no public sign of accepting Ghani's offer, instead issuing several statements suggesting they meant to keep fighting.
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"In other words, it may not be that the whole Taliban comes over in one fell swoop", he stated.
Speaking to reporters on the plane, Mattis reiterated that the United States defines victory in Afghanistan as political reconciliation, not a military victory. Put another way - the aim is to convince the insurgents they can not win on the battlefield, thus driving them to reconcile with the Afghan government.
Ghani recently offered the Taliban recognition as a political party, freeing of their prisoners and removal of sanctions in return for end to fighting, shunning ties with foreign terrorists and respecting the Afghan Constitution.
Mattis says the uptick in Taliban attacks on civilians show the insurgency can not gain more territory.
They said that while Afghan forces are getting better, the Taliban is likely to threaten Afghan stability in 2018.
They have offered to talk directly to the United States about a possible peace agreement.
Mattis was speaking to reporters before landing in Kabul for an unannounced visit there during an global trip.
Mattis has said that the USA goal is to enable Afghan forces to weaken the Taliban to the point where the Afghans can manage their own security.
Reconciliation, Mattis said, was "almost an equal priority of my interest going in".