Ship nets were carried onboard Vagaari ships in a collapsed position and when deployed would take on a spherical shape. They would then produce gravity similar in magnitude to that of a planet. This mass shadow would cause nearby ships to be unable to jump to hyperspace. It would also cause any ship crossing its path in hyperspace to be yanked back into real space.
Thrawn stole one of these ship nets and used it to trap a Trade Federation Task Force, Outbound Flight, and the Vagaari Fleet themselves. Due to Thrawn's tactical genius and their inability to escape, all three groups were crippled or destroyed. Presumably, Thrawn later handed the ship net, along with the remainder of the defeated Vagaari Fleet, over to the Chiss Government for study and reverse engineering.
Interdictors were used by Thrawn while he was Grand Admiral in the Galactic Empire. Thrawn's information on the Vagaari ship nets may have been the basis for Imperial Interdictor technology. That technology was later passed to the Galactic Alliance and the Hapes Government.
Behind the scenesEdit
Interdictor technology plays a heavy role in most of the novels written by Timothy Zahn. Interdictors were first used by the Empire in Zahn's Thrawn Trilogy. In his prequel, Outbound Flight, he describes Thrawn first obtaining the technology from the Vagaari. In the books, it is described as new technology, however, the technology appears in Knights of the Old Republic, which takes place nearly 4000 years before the Thrawn books. This is retconned by the Star Wars Database by indicating that the interdictors in the KotOR time period are far less powerful, and no longer effective in the Empire's time period due to improvements in hyperdrive design.