The tri-cobalt warhead is a high yield subspace device used for large scale destruction of stationary targets such as space stations.

Although the Federation is banned from using subspace weapons by the Khitomer accords, Starfleet vessels do carry tri-cobalt devices occasionally. In 2371 the USS Voyager used two of them to destroy the Caretaker’s array in order to prevent it from falling into the hands of the Kazon. The Starfleet weapon has a programmable yield which can reach 20,000 Teracochranes, more than enough to destroy even a large station like the Caretaker’s array.