US Defense Secretary Chuck Hagel arrived in Afghanistan on an unannounced visit Sunday, a US defense official said, following the release of soldier Bowe Bergdahl after five years in Taliban captivity.

US Defense Secretary Chuck Hagel arrived in Afghanistan on an unannounced visit Sunday, a US defense official said, following the release of soldier Bowe Bergdahl after five years in Taliban captivity.

Hagel arrived at Bagram Airfield, a US-controlled vast military base north of Kabul, according to the official who spoke on condition of anonymity.

Bergdahl's release in exchange for five senior Taliban figures held at Guantanamo Bay has been hailed as a breakthrough for peace efforts by a senior member of Afghanistan's High Peace Counil.

But it has come under fire from some US lawmakers.

Hagel's trip comes a week after President Barack Obama made a  surprise trip to Afghanistan as combat troops prepare to pull out by the end of this year.

Upon his return Obama outlined a plan under which a US force will remain in the country until the end of 2016 on a training and counter-terrorism mission -- subject to the signing of a long-delayed Bilateral Security Agreement.