US Defence Secretary Leon Panetta arrived on an unannounced visit to Afghanistan Wednesday, the NATO-led military said, dpa reported.
"We can confirm that the US defence secretary is now in Kabul," Amy Hession, a NATO spokeswoman told dpa.
She did not say how long Panetta, on his fifth trip to Afghanistan since his appointment last year, was planning to be in the country.
Panetta is expected to meet with Afghan President Hamid Karzai who is currently in Turkey to discuss Taliban reconciliation efforts with Pakistan, and will return on Thursday.