KABUL (AFP) - US Defense Secretary Ashton Carter arrived in Afghanistan Friday (Dec 18) on an unannounced visit, officials said, with media reporting his trip was aimed at assessing the deteriorating security situation in the country.

His visit comes amid an upsurge in Taliban attacks across Afghanistan and mounting concerns that loyalists of the Islamic State group are making steady inroads in the country.

"(Carter) has landed" in Afghanistan, the Pentagon said in a brief statement.

The US embassy in Kabul also confirmed his arrival, but shared no details on the purpose of his visit.

Local media said the surprise visit, which comes after a brief stopover in Iraq, is meant to assess the fragile security situation in Afghanistan.

Fuelling those concerns is a new Pentagon report released earlier this week which reported a surge in insurgent attacks in the second half of 2015.

This month marks a year since the US- and NATO-led mission in Afghanistan transitioned into an Afghan-led operation, with allied nations assisting in training local forces.