On the night of 29-30 November, an explosion occurred on the Baikal-Amur Mainline in the Severomuysky Tunnel, named after Vladimir Bessolov, located in Buryatia (Russia).
Source: Ukrainska Pravda’s source in the security forces
Details: The source notes that this is actually the only major railway connection between Russia and China. And currently this route, which Russia uses, specifically for military supplies, is paralysed.
I guess it’s all desert or tundra for most of that border, I also assumed there were more crossings