Planetary blockade
A planetary blockade is the state of a system in Star Wars: Rebellion that has a fleet in orbit above it while the system is enemy or neutral to that fleet's side, which complicates any movement of units onto or off the system.[1]
Effects
A fleet that orbits an enemy or neutral system blockades it automatically. Under a blockade, troops that try to move may be killed, and personnel that try to cross it may be injured, killed or captured.[1]
Ion cannons
Ion cannons on the blockaded system let units pass through.[1] The KDY-150 is the ion cannon in the game's defensive facilities. It saps the attacker's energy, which knocks out its shields and stops it firing. The manual says a blockading fleet cannot detect missions, injure characters or destroy Special Forces passing through its position over a system that has an ion cannon.[2] The manual's battery chart adds that an ion cannon makes it easier for troops, characters and Special forces to escape under blockade or bombardment.[3]
Preventing a blockade
The manual lists strong defense fleets, where a player has them, or fighter squadrons stationed on the system as ways to prevent an opposing fleet from starting a blockade.[4]