Collective security: League of Nations and United Nations
Collective security is a promise among states: an attack on one is a problem for all, so all act together to stop it.
- League of Nations (1920): formed after World War I. It had no army of its own, some big states were not members or left, and it needed agreement to act. It failed to stop attacks in the 1930s.
- United Nations (1945): formed after World War II. Its Security Council has 5 permanent members (China, France, Russia, UK, USA) and 10 elected members. It can order sanctions, and it can send peacekeepers. The General Assembly lets all members speak. The UN also works on health, children, refugees and development.
The Cold War and why the UN was often stuck
From 1945 to 1991 two superpowers, the USA and the USSR, led rival blocs. They did not fight each other directly but competed in arms, space and influence, and fought through other countries (proxy wars).
Each permanent member of the Security Council has a veto: one "no" can block a decision. In the Cold War the two sides often vetoed each other, so the UN could not act on many crises. Even so, it helped in other ways, such as with peacekeepers, aid and talks.
Many new countries, such as India, tried to stay out of both blocs. This was the Non-Aligned Movement.
Arms control
Arms control means countries agree to limit, reduce or stop the spread of weapons. The Cold War arms race put thousands of nuclear warheads in the world. Key steps:
- 1963 Partial Test Ban: no nuclear tests in air, space or sea.
- 1968 Non-Proliferation Treaty (NPT): stop new countries getting nuclear weapons.
- 1972 SALT I: first limits on the two superpowers.
- 1987 INF: removed a whole class of missiles.
- 1991 START: first big cut in long-range weapons.
Thousands of warheads still exist, so the work continues.
Try it: build your own ring
In the 3D free-play step, guess how many of 10 states must act to stop an attacker, then check. At home, list 3 rules in your class that work only if everyone follows them. What happens if some do not?
Key formulas and definitions
- League of Nations: 1920, no army, failed in the 1930s
- United Nations: 1945, Security Council = 5 permanent + 10 elected
- Veto: one permanent member can block a decision
- Cold War: 1945-1991
- Arms control: 1963 test ban, 1968 NPT, 1972 SALT, 1987 INF, 1991 START
Worked examples
1. Give two reasons why the League of Nations was weak.
It had no army of its own, and some big states stayed out or left. It also needed agreement among members to act.
2. What is a veto, and why did it matter in the Cold War?
A veto lets one permanent member of the Security Council block a decision. In the Cold War the two sides vetoed each other, so the UN often could not act.
3. What is the aim of the Non-Proliferation Treaty (1968)?
To stop nuclear weapons spreading to more countries, while promising to work towards disarmament.
Common mistakes
- Mixing up the League (1920) and the UN (1945).
- Thinking the Cold War was a direct fight between the USA and USSR: it was fought through other countries and arms races.
- Saying the UN has only 5 members on the Security Council: 5 permanent plus 10 elected.
- Thinking arms control means all nuclear weapons are gone: thousands still exist.