Pat Shanahan, acting Pentagon chief, in unannounced visit to Afghanistan

Pat Shanahan, acting Pentagon chief, in unannounced visit to Afghanistan

The Special Representative for Afghanistan Reconciliation Zalmay Khalilzad pictured on Friday at the US Institute of Peace, in Washington.

After almost 18 years of US-led war in Afghanistan, the acting Pentagon chief, who temporarily took over after James Mattis resigned over Trump's decision to pull out of Syria, said that Afghanis must decide they future on "their own" - including how to deal with the Taliban.

Trump has offered no specifics about when he would bring home USA troops from Afghanistan but has said progress in negotiations with the Taliban would enable a troop reduction and a "focus on counter-terrorism".

"It is important that the Afghan government is involved in discussions regarding Afghanistan", Shanahan told a small group of reporters traveling with him on the unannounced trip.

Some in Afghanistan have opposed any peace deal with the Taliban, while the Taliban has so far refused to negotiate with the government in Kabul, calling government officials puppets of the West.

US President Donald Trump has publicly questioned the benefits of a continued military presence in Afghanistan, and ordered the military to pull out of Syria in December.

"We will bring a lasting and honourable peace to the country", he said.

At an extraordinary moment in Pentagon history, a former business executive with little political stature and without military experience is making his worldwide debut as the acting US defense secretary.

Acting U.S. defense secretary Patrick Shanahan arrives in Kabul, Afghanistan February 11, 2019.

It was not immediately clear if Shanahan and Khalilzad would be conducting joint discussions during their trips.

He also said his goal on the trip was to get an understanding of the situation on the ground from commanders and then to brief Trump on his findings. Those include the involvement of the Afghan government, which the Taliban refuse to acknowledge.

The next round of talks is due in Qatar on February 25. Some U.S. forces also carry out counter-terrorism operations.

However, he told reporters, he has no particular instruction from the administration about any slashing of the American troop presence in Afghanistan from the current 14,000 soldiers.

"We do not know whether we will achieve an agreement", Trump said in his State of the Union address to Congress last week, "but we do know that after two decades of war, the hour has come to at least try for peace".

The pace of any US troop withdrawal from Afghanistan has been a major point of discussion - and concern - given the strength the Taliban still wields and the group's well-established history of hosting terror groups.

The Taliban have put out contradictory information on what timeline the United States has agreed to in any potential withdrawal.

It was Shanahan's first-ever visit to Afghanistan, where American troops have been at war for 17 years and the Trump administration is pushing for a peace deal with the Taliban.

Afghanistan's special forces units suffered increasingly heavy casualties a year ago as the Taliban mounted major assaults on provincial centers including Ghazni and Farah in the southwest.