"Australia has said its warplanes took part in US-led airstrikes in eastern Syria that mistakenly killed Syrian army troops in an incident threatening to wreck an already tenuous ceasefire before it is a week old... An Australian defence department statement said its jets had targeted what had been thought to be Islamic State (Isis) fighters... The US [and Australia] has offered condolences and insisted that the airstrikes were a mistake. It said it had targeted Tharda mountain where a Syrian government offensive was seeking to capture Isis positions overlooking the Deir ez-Zour military airport." (Australian warplanes took part in airstrikes that killed Syrian troops, Julian Borger, The Guardian, 19/9/16)
"Thardah mountain is made up of 6... hills, all under SAA control with no prior presence of Isis on them./ [It] has always been under SAA control, bar a small breach a few months ago, which was quickly reversed./ So again CENTCOM's statement in which it says coalition has bombed these positions in the past is puzzling." (Tweets by former Sunday Times journalist Hala Jaber, 18/9/16)
Incidentally, Israel has been the only country up to now killing Syrian troops on Syrian soil.
PS: "In the defense of the Deir Ezzor Airport, the Syrian military has long depended on an army base in Jebel Tharda to repel ISIS advances. That base has been lost this weekend, after a disastrous series of US-led airstrikes killed a large number of Syrian troops defending the base, and ISIS quickly overran what was left." (ISIS overruns Syrian army base after US bombings, Jason Ditz, antiwar.com, 18/9/16)