The shooting down of the Syrian SU-22 fighter appears to have been intended as a warning to stop the Syrian army from capturing Rusafa, so as to block the Syrian army’s attempt to relieve the pressure on Deir Ezzor.Kurdish state in northern Syria still on the table.
The Russian warning to the US looks in turn to have been intended to make clear to the US that this sort of interference in the Syrian army’s operations to relieve Deir Ezzor is unacceptable and will not be tolerated.
The US has heeded the Russian warning. The various statements made by the US and by various US officials today, though full of the usual bluster about the US defending itself and its allies anywhere and everywhere, in fact clearly signal that the US is backing off.
 "BREAKING: No partition of eastern Syria; US 'welcomes Syria destroying ISIS' there." By Alexander Mercouris, The Duran, 6/25/17.