[achierius]

> Who built all Russia's oil infrastructure ?

The Soviet Union? Yeah, the new offshore stuff (mostly? developed after the fall of the USSR) relied on western firms, but I believe the bulk of oil production still comes from / goes through domestically sourced systems. Gas production on the other hand was initially almost entirely built out by western firms, though that's obviously begun to change since the war in Ukraine.

[hylaride]

A not insignificant percentage of Soviet-era drilling and pipeline pumping equipment and tech is/was western. There's even many allegations of CIA sabotage before delivery (which is hard to prove).