Plus, not every country has every resource. Even the vast internal resources of the USSR needed to be supplemented by goods and services purchased on the open market (and vice-versa, the USSR got most of its hard currency by selling oil).
Plus, not every country has every resource. Even the vast internal resources of the USSR needed to be supplemented by goods and services purchased on the open market (and vice-versa, the USSR got most of its hard currency by selling oil).