Yes, this explains what we've seen. Russia couldn't produce a single Su-27 without international trade. No country could. The lack of day-one air domination might be explained by this. They don't dare risk a precious asset in the expectation of years of sanctions.

Also, they're rolling out aging and poorly maintained armor, because that's what they manufactured at home. But it's the 21st century. Drones and shoulder-launched self-guiding munitions are cheap hard counters. I wouldn't want to be trapped inside a tank today!

As far as Syria goes, it wasn't facing off against another army. They struggled to stop a multitude of powers and factions fighting them and each other for years. Only the lack of a united opposition, and Russia's support, allowed that regime to persist. Shelling civilians with poison gas might work in Syria, but the whole world is watching Ukraine.