* U.S. says it sees signs of Taliban willingness to talk
* Afghan president offered talks without preconditions
* Diplomats say contact involving intermediaries is underway
* No public sign of Taliban accepting Afghan leader's offer (Adds U.S. comments, context)
By Phil Stewart
KABUL, March 13 (Reuters) - The United States is seeing signs of interest from elements of Afghanistan's Taliban insurgency about talks with Kabul to end the more than 16-year-old war, U.S. Defense Secretary Jim Mattis said on Tuesday, as he made an unannounced visit to Afghanistan.
Mattis offered few details about the Taliban outreach and it was unclear whether the latest reconciliation prospects would prove any more fruitful than previous, frustrated attempts to move toward a negotiated end to America's longest war.
Taliban fighters still control large parts of the country and any new battlefield gains by U.S. and U.S.-backed Afghan forces cannot promise to overcome Afghanistan's yawning political divisions and entrenched corruption.
"We've had some groups of Taliban - small groups - who have either started to come over or expressed an interest in talking," Mattis told reporters traveling with him.
Mattis comments came during a trip to Afghanistan that is expected to precede a sharp increase in fighting after U.S. President Donald Trump approved a more aggressive strategy against the insurgents last year that included more U.S. combat advisors and air strikes.
That reversed a trend of scheduled drawdowns under his predecessor, Barack Obama, and set the stage for an open-ended conflict.
Trump has also piled pressure on Pakistan to crack down on militant safe havens on its side of the Afghan-Pakistan border. Mattis noted some positive indications from Islamabad, including Pakistani military operations along the border.
Trump has made no secret of anger toward Pakistan or his pessimism about Taliban peace talks, declaring on Jan. 29 after a series of Taliban attacks in Afghanistan: "I don't see any talking taking place."
But Afghan President Ashraf Ghani offered talks without preconditions with the Taliban insurgents last month, in what was seen by U.S. officials as a major overture from Kabul.
Ghani, hosting Mattis at his presidential palace in Kabul, described the new U.S. strategy as a game changer, allowing Kabul to extend its peace offer to the Taliban without doing so from a position of weakness.
Afghanistan experts have long worried that a precipitous U.S. exit could usher in defeat for the Afghan army.
"It has been a game changer because it has forced every actor to re-examine their assumptions," Ghani 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 centre in western Afghanistan this week, have given no public sign of accepting Ghani's offer, instead issuing several statements suggesting they intended to keep fighting.
U.S. Army Brigadier General Michael Fenzel, a top coalition official, said he interpreted the Taliban's silence as a positive signal that the Taliban were considering Ghani's offer.
"I also wonder whether or not they're saying to themselves perhaps this is the best negotiating position (we) will ever have," Fenzel said.
Mattis stressed that the military campaign was aimed at driving the insurgents toward a political reconciliation, as opposed to an outright battlefield defeat.
"It may not be that the whole Taliban comes over in one fell swoop. That may be a bridge too far to expect," Mattis said.
"But there are elements of the Taliban clearly interested in talking to the Afghan government."
Uzbekistan is set to host an Afghan peace conference this month, where participants are expected to call for direct talks between the militant group and Ghani's government.
However, the Taliban appears likely to miss that conference and have ruled out direct talks with the Western-backed government in Kabul, which they say is an illegitimate, foreign-imposed regime.
They have offered to talk directly to the United States about a possible peace agreement.
Asked whether the United States would be willing to talk directly with the Taliban, Mattis reiterated the U.S. position that the talks should be led by Kabul.
"We want the Afghans to lead and provide the substance to the reconciliation effort," Mattis said. (Additional reporting by James Mackenzie Editing by Paul Tait and James Dalgleish)
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