In the 2260s, Captain James T. Kirk and Lieutenant Commander Spock visited Asteroid Delta. While there, they successfully defended it against an attack by unspecified forces. Kirk thought of the incident as the Siege of Asteroid Delta.
In 2266, Spock was captured by a terrorist on Fayo who gave Kirk three minutes to trade Spock's life for that of Prince Yano, son of Emperor Bavoda. Starfleet orders disallowed terrorist negotiations, forcing Kirk to consider having to leave his friend to die. Spock reiterated that Kirk should obey Starfleet orders rather than save his life. At that moment, a thousand images went through his head, including memories of their time on Asteroid Delta. Kirk also recalled incidents with the Brain Ray Robot and Duanda. (TOS comic: "Prince Traitor")