US Defense Secretary Ashton Carter
© AP
US Defense Secretary Ashton Carter arrived in Afghanistan Friday on an unannounced visit, local media reported.

According to the Khaama Press news agency, Carter is expected to meet with Afghan officials and military commanders, as well as with the US troops deployed in the country.

His visit comes amid a deteriorating security situation in Afghanistan. The Pentagon said in a report on Tuesday that the Afghan national security forces had reported a 27 percent increase in casualties since the start of the year.

Afghanistan is facing threats from both Afghan insurgency and extremist networks, including the Taliban, the Haqqani Network, and al-Qaeda.

The US-led NATO mission formally ended its International Security Assistance Force combat operations in Afghanistan on December 31, 2014, but it has transitioned to a non-combat mission in the country. In October, US President Barack Obama said he would prolong the US military engagement in Afghanistan by maintaining a force of 9,800 through most of 2016.