In the Kelvin timeline, Sarek's scout ship was Federation scout ship in service to the Vulcans. (TOS comic: "Vulcan's Vengeance, Part 1")
History[]
Escape from the Enterprise.
In 2259, Ambassador Sarek and his followers disguised themselves as crewmembers of the rogue Romulan starship Narada and raided a D'Kyr-class Vulcan science vessel in the 40 Eridani A star system. They stole the red matter recovered by the Vulcan scientists from the former location of planet Vulcan. The Starfleet starship USS Enterprise arrived to lend aid the science vessel, prompting Sarek's scout ship to escape into Romulan space.
Sarek planned to detonate the red matter on Romulus to take revenge for the destruction of Vulcan in 2258. (TOS comic: "Vulcan's Vengeance, Part 1")