"He is scheduled to pay tribute to Army Sgt. Yoon Jang-ho in a visit later today to a monument for him at the US Army Garrison Yongsan," the source told Yonhap News Agency.

Yoon was killed in 2007 when a bomb went off at the main gate of a US air base in Bagram, some 80 kilometers north of the Afghan capital, Kabul. He was 27 years old and a sergeant at the time. He was posthumously promoted to staff sergeant.

He was the first South Korean soldier killed in action abroad since the Vietnam War.

The US Forces Korea set up the stone monument and planted a tree inside the garrison to commemorate his sacrifice.

Traveling to Kabul in January, Shannon reaffirmed Washington's continued commitment to the war-torn country's security and prosperity. (Yonhap)