You overestimate how long it would take to build a pipeline from China to Russia in wartime with no regard to cost. The transsiberian railway isn't operating a

You overestimate how long it would take to build a pipeline from China to Russia in wartime with no regard to cost. The transsiberian railway isn't operating anywhere near the capacity of the rail itself, it just doesn't have enough rolling stock. The recent upgrades weren't to increase maximum capacity, they were to increase capacity at cost by increasing maximum train length and maximum speed. Nothing prevented there to simply be more trains, it's just less economical. In wartime this matters little.