"Russia supported the Ba'athist administration of former President Bashar al-Assad of Syria from the onset of the Syrian conflict in 2011: politically, with military aid, and (from September 2015 to December 2024) with direct military involvement."
yes soviet union had diplomatic relations with Syria as well as other arab states, but Russia didn't involve in Syrian civil war instigated by the CIA (so called Arab Spring) and completely fumbled by Barry Soetoro
Supplying weapons to whom? It was bona fide weapons purchases program from one state to another, like all other states procure their weapons.
Syrian war was civil war financed by the NED, USAID and other US entities to topple Assad, like they did in other arab spring states.
It took several years of civil war and unsuccessful bombing of civilians by Barry Soetoro, unsuccessful funding of various jihadi groups by the Pentagon and CIA (separately), the same groups that led to the rise of ISIS. Only then by the request from then president Assad, did Russia help with strikes against ISIS
Please don't try to put the blame on Russia, where it squarely belongs to the USA
https://en.wikipedia.org/wiki/A_Clean_Break:_A_New_Strategy_...