Military action is always tied to economics. Or at least it should be from a realism perspective. When we don’t tie them together as part of a combined objective, we fail. Our security action in Afghanistan had no synced economic effort, so no one (including us) had any financial incentive to see it through. Postwar Germany and Japan were successful because of massive economic investment tied to a permanent security presence.
In a sort of reverse case, massive economic investment that isn’t backed up by military security will eventually fail, like when Iraq rolled into Kuwait uncontested. At that point, a military action by an outsider is needed to restore the previous situation, because our Allies didn’t want Kuwait’s oil to be controlled by Saddam. Nor did they want Saddam to conquer them also, which seemed like a legitimate threat in 1990. In Ukraine’s case, our European Allies don’t want Ukraine’s resources to be controlled by Russia, and a Russian expansion also seemed like a legitimate threat in 2021.