The Canadian navy said one of its frigates and an American navy ship both suffered minor damage after a collision off the coast of Florida.
The Canadian Forces said HMCS Fredericton "briefly came into contact" with USNS Kanawha during a routine manoeuvre.
The Forces said there were no injuries, but both ships suffered "superficial" damage consisting of scrapes and dents on both hulls.
The cause of the collision, during a replenishment-at-sea manoeuvre, is under investigation.
Such a manoeuvre involves one ship taking on fuel and other supplies from another while both ships are in motion.
Both ships are involved in an exercise taking place off the east coasts of Canada and the United States for most of November.