The Vulcan government's security service, for which the young T'Pol once hunted renegade agents, a mission whose buried trauma resurfaces when she is sent after the fugitive Menos.
The Ministry of Security is the Vulcan agency responsible for intelligence and covert operations in the twenty-second century. T'Pol served in it before her posting to Earth.
Its work is examined in the Enterprise episode The Seventh. Years earlier the Ministry had placed surgically altered agents on the planet Agaron, and a number of them refused to come home. T'Pol was one of the officers sent to bring them back. Now the Ministry orders her to seize Menos, the last still at large, and she asks Archer and Mayweather to go with her.
The pursuit unlocks a memory the Ministry had helped her suppress through a ritual at P'Jem: there had been another fugitive, Jossen, whom she shot dead. Shaken, she nevertheless completes the arrest.