An Afghan security force member takes part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)

Afghan security force members take part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)

Afghan security force members take part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)

Afghan security force members take part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)

An Afghan security force member takes part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)

Afghan security force members take part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)

Afghan security force members take part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)

An Afghan security force member takes part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)

Afghan security force members take part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)

Afghan security force members take part in a military operation in Khogyani district of Nangarhar province, eastern Afghanistan, Dec. 24, 2018. ( Xinhua/Saifurahman Safi)