Pactomania is a term originally created to describe the period between 1945 and 1955, during which the United States concluded or ratified a significant amount of alliances, treaties, and pacts. The word pactomania was first used in a New York Times article in 1955.

The Australia, New Zealand, United States Security Treaty is a 1951 non-binding collective security agreement initially formed as a trilateral agreement between Australia, New Zealand, and the United States; and from 1986 an agreement between New Zealand and Australia, and separately, Australia and the United States, to co-operate on military matters in the Pacific Ocean region, although today the treaty is taken to relate to conflicts worldwide. It provides that an armed attack on any of the three parties would be dangerous to the others, and that each should act to meet the common threat. It set up a committee of foreign ministers that can meet for consultation.