Julin Bristol is the codename given to a nuclear weapon test conducted at the Nevada Test Site on 26 November 1991. Conducted as part of Operation Julin, the final series of US nuclear tests, it was the last test explosion of a British nuclear weapon. Both the US and UK, as signatories of the Comprehensive Nuclear-Test-Ban Treaty, ceased nuclear testing after Operation Julin. With a yield of less than 20 kilotons, it may have been a proof test of some aspect of the British-designed warheads fitted to the submarine Trident missiles in the British arsenal, possibly of a low yield mode.