Proponents of the league of nations envisioned it working under a concept called collective security, under which if any country attacked another, all of the other countries in the league would unify and come to the aid of the country under attack. Most american opponents of the league of nations argued that, by joining it, the united states would give up a degree of independence. But even if every league action benefited the united states, can you find any weaknesses in the idea of collective security itself?.