Collective security

A system in which countries cooperate to protect one another against aggression.

The principle that countries should act together to protect peace and resist aggression, rather than leaving each threatened country to defend itself alone.

The principle that countries should act together against an aggressor to protect the peace and security of all members.

The principle that countries should act together against aggression, rather than leaving the country under attack to defend itself alone.

The principle that countries act together to defend a member that is attacked.