Russia was responsible for bombing a United Nations convoy outside Aleppo, Syria Monday killing at least 12 aid workers, a U.S. official told Fox News on Tuesday.
The U.N. aid agency is suspending all convoys in Syria -- putting an already fragile cease-fire agreement between the U.S. and Russia into further doubt.
Also read: Syria Seizes Parts of Aleppo From Rebels
20:38 Syria war: Army makes rapid gains in rebel-held east Aleppo7
09:03 IAF strikes ISIS-linked cell in Syria after cross-border fire on Golan12
10:51 'Aleppo is going to die'; thousands flee government bombing of Aleppo12
05:06 Syria war: Thousands uprooted from rebel-held east Aleppo23