The SGC has used laser-guided missiles to launch an off-world attack through the stargate. Using remote control from the SGC, the UAV can be launched through the stargate, carrying a laser pointer that will "paint" a target off-world. When missiles are then launched through the gate, they are guided by the laser to their target. Without a laser-painted target, the missiles would fly out their fuel and crash. SG-1 used the guided missiles on Latona in order to eliminate Svarog's Jaffa guard at the gate and allow a team to come through. The missiles were also used as part of a coordinated plan to eliminate Moloc and his forces. The UAV was shot down, however Teal'c and Aron recovered the laser from the downed UAV and pointed it manually to direct the missiles to their target, Moloc himself. The Trust also used VX rockets fired through the stargate without the need for a laser guided system, in order to deliver symbiote poison to Goa'uld controlled worlds.
Cross Reference: Moloc, Trust, UAV, Weapons
Episode Reference: The Sentinel, Sacrifices, Endgame