Alternate timeline
(covers information from an alternate timeline)
A mutual defence pact was an agreement made by two governments to protect each other's interests.
In the 25th century, an elderly Jake Sisko recalled how, after his father Benjamin Sisko disappeared, the Cardassians entered a mutual defence pact with the Bajorans, as the latter believed their Emissary's vanishing as a sign from the Prophets that they couldn't count on the United Federation of Planets for protection from the Klingons. (DS9: "The Visitor")