The fog of war sits heavily over the circumstances of a clash between the United States and Syrian forces last week.
Now the potential death of an unknown number of Russians in the intense battle threatens to further destabilise an already tumultuous situation.
Some unsubstantiated Russian social media sources are claiming a "massacre" of two mercenary fighting units. One was reportedly wiped out, and the other "cut to pieces" by US firepower, killing up to 200 Russian nationals.
Other sources say a "handful" of contracted Russian advisers were caught up in the onslaught.
Russian news service Komsomolskaya Pravda reports anonymous sources as saying: "They simply rolled us ... Artillery first, then helicopters .. Surely they saw that we were preparing for an assault on our beachhead on the left bank ... As a result, almost everyone from the 5th assault detachment died, they were burnt together with their hardware."
At the heart of the scenario is an assault last week by some 500 pro-Syrian President Assad regime troops on an Deir al-Zor encampment of US-backed Syrian Democratic Force (SDF) rebels.
US Defense Secretary General James Mattis said over the weekend he did not understand the circumstances behind the confusion — as well established lines of communication and procedures had been used to prevent just such an incident.
"The Russians told us they had no forces there initially. I think that's still the case but we don't have full clarity on what the regime forces are doing there.
"The Russians professed that they were not aware when we called them about that force that had crossed the Euphrates. As it came closer they were notified when the firing began."
But Russian media has been filled with reports of dead nationals — killed by US fire in Syria's Deir el-Zour province.
New Zealand Herald