The State Department said the trip "is part of an overall effort to facilitate a peace process that protects U.S. national security interests and brings all Afghan parties together in an intra-Afghan dialogue through which they can determine a path for their country's future".
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.
There is no plan on either to withdraw or reduce the number of U.S. forces in Afghanistan, a spokesman for USA forces, Colonel David Butler said, adding that they will continue their support to their Afghan counterparts to thwart threats against Afghanistan and the United States, even after a political agreement with the Taliban.
The emphasis on bringing "all Afghan parties together" appeared crucial.
Shanahan will meet Afghan President Ashraf Ghani, whose government was not part of major talks between United States and Taliban officials last month that negotiators hope could bring a breakthrough in the 17-year conflict.
The US envoy's most recent talks were in Doha late last month where the two sides met for six days.
US Special Representative for Afghanistan Reconciliation Zalmay Khalilzad left Washington on Sunday on yet another peace mission that includes talks in Afghanistan, Pakistan and Qatar.
President Donald Trump has been pushing to end U.S. involvement in Afghanistan, where 14,000 American troops are still deployed. But Khalilzad emphasized that any troop withdrawal would depend on conditions on the ground.More news: Google Pixel 4 could come with improved dual-SIM support
More news: Apparently, Jennifer Aniston Is "Very Happy" Brad Pitt Attended Her Birthday Party
More news: USA envoy: Pakistan freed Taliban leader at United States request
Butler said the US-backed military pressure by Afghan forces on the Taliban will continue until the group endorses the peace process.
While on his way to Afghanistan Shanahan stressed that peace terms are for the Afghans to decide.
The Trump administration's special envoy for Afghanistan is returning to the country after stops in Europe and the Middle East for an extended diplomatic tour aimed at pushing a US peace initiative.
Acting U.S. defense secretary Patrick Shanahan arrives in Kabul, Afghanistan February 11, 2019.
Shanahan will meet General Scott Miller, the top USA and North Atlantic Treaty Organisation commander in Afghanistan, during his visit.
"It is important that the Afghan government is involved in discussions regarding Afghanistan", Shanahan told reporters accompanying him, as cited by Reuters.
The issue of United States forces withdrawal from Afghanistan has been one of the key preconditions by the Taliban to attend direct talks with the Afghan government.
While the US talks with the Taliban have focused on troop presence and assurances that terrorist networks would not be given haven, Khalilzad said intra-Afghan talks could also deal with human rights, freedom of the press and the role of women, who were harshly oppressed under Taliban rule. "I think the presence we want in Afghanistan is what assures our homeland defence and supports regional stability".