Short answers, pulled from the story.
The intervention ran from September 2015 to December 2024. It began when Bashar al-Assad requested Russian support against the Syrian opposition and Islamic State, and it ended after Assad fled the country following the fall of Damascus.
Russia intervened to prevent the collapse of its ally Bashar al-Assad, whose government controlled only 26 percent of Syrian territory before the intervention began. Analysts also pointed to strategic goals such as limiting United States influence in the Middle East, securing access to the Eastern Mediterranean, and blocking a proposed Qatar-Turkey gas pipeline that would have competed with Gazprom.
By January 2017, the Russian Air Force was claimed to have flown 19,160 air combat missions and delivered 71,000 strikes. By late August 2017, that total had grown to about 28,000 combat missions and roughly 90,000 strikes.
Estimates vary by source and period. Russian airstrikes reportedly killed more than 7,700 civilians by April 2018, and separate estimates put civilian deaths from Russian aerial campaigns between September 2015 and March 2019 at around 8,000 out of roughly 18,150 total deaths.
The Wagner Group was one of the Russian private military companies that carried out ground operations in Syria alongside special forces and military advisors, while Russia's regular forces retained control of the air campaign.
It ended after a Syrian opposition offensive in November 2024 that Russian airstrikes failed to stop. Assad fled the country in December 2024, and Russia withdrew forces from its bases; by the 24th of January 2025, Syria had terminated the 49-year lease agreement for the Tartus naval facility.