US Defense Sec'y Mattis in Afghanistan to discuss war needs

Qatar's Emir Sheikh Tamim Bin Hamad Al-Thani, right, greets U.S. Defense Secretary Jim Mattis at his residence, the Sea Palace, in Doha, Qatar, Saturday, April 22, 2017. (Jonathan Ernst/Pool Photo via AP) (The Associated Press)

Qatar's Emir Sheikh Tamim Bin Hamad Al-Thani, right, talks with U.S. Defense Secretary Jim Mattis, center, and U.S. Ambassador to Qatar Dana Shell Smith at his residence, the Sea Palace, in Doha, Qatar, Saturday, April 22, 2017. (Jonathan Ernst/Pool Photo via AP) (The Associated Press)

U.S. Defense Secretary Jim Mattis checks his watch as he arrives via helicopter at Resolute Support headquarters in Kabul, Afghanistan Monday, April 24, 2017. (Jonathan Ernst/Pool Photo via AP) (The Associated Press)

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.