U.S. still unsure who directed Syria attack, despite Russian dead

U.S. Secretary of Defence Jim Mattis addresses a news conference during a NATO defence ministers meeting at the Alliance headquarters in Brussels, Belgium, February 15, 2018. REUTERS/Francois Lenoir

WASHINGTON (Reuters) - The United States is still unsure who directed a Feb. 7 attack on U.S. and U.S.-backed forces in Syria, Defense Secretary Jim Mattis said on Saturday, even as he acknowledged accounts that Russian civilian contractors were involved.

Reuters has reported that about 300 men working for a Kremlin-linked Russian private military firm were either killed or injured in Syria.