A faction from the far future that rejected the Temporal Accords and, stranded in an altered 1944, armed Nazi Germany in exchange for the means to build a time conduit home.
The Na'kuhl are the last and most dangerous faction of the Temporal Cold War, appearing in the Enterprise two-part story Storm Front. Their leader Vosk despises the Temporal Accords and developed a form of stealth time travel, and the agent Daniels regards him as the gravest threat he has faced.
Pursued through time, Vosk and his followers are marooned in the 20th century. Their interference removes Lenin from history, which lets Germany overrun Europe and invade the eastern United States, and they trade advanced weapons to the Nazis for the resources to build a conduit near occupied New York.
Jonathan Archer, deposited in this altered 1944 with Enterprise, works with American resistance fighters and the Suliban Silik to breach the facility. Enterprise destroys the conduit as Vosk tries to use it, the timeline resets, and Daniels tells Archer the Temporal Cold War is over.