KABUL, Afghanistan (AP) — U.S. Defense Secretary Jim Mattis has arrived unannounced in Afghanistan.

Mattis is in Kabul to assess America's longest war as the Trump administration weighs sending more U.S. troops. His visit comes three days after a Taliban attack on a northern Afghanistan army base killed at least 100 people, with some estimates up to 130.

For Mattis, Kabul is the final stop on a six-nation, weeklong tour by the Pentagon chief intended to bolster relations with allies and partners and to get an update on the stalemated conflict in Afghanistan.

Mattis is the first member of President Donald Trump's Cabinet to visit Afghanistan. The top American commander in Kabul, Gen. John Nicholson, recently told Congress that he needs a few thousand more troops.