It is when a country attacks another country (or entity) that it fears may plan to attack it later. In other words, it takes action not because of
factual threat but of mere potential risk. The
precautionary principle is also applied when someone is detained or
jailed not because of what he has actually done but because of what the government or police think he may potentially do.
The United States attacked and occupied
Iraq using the Precautionary
Principle. Nothing would prevent it to use the same
principle to attack
Iran.
