Shields provide partial protection against Missile Attacks and they add a strength of 6 in battles. Shields begin as Level 1 and can be upgraded twice, up to Level 3. Higher-level shields are more resistant to Missile attacks, but provide no additional defensive strength in battle.
Upgrades cost of 3E and can be performed during the Muster Phase, or during the Re-arm Bonus Military Action. Upgrades are allowed if a faction merely has a friendly presence in the grid space (Units or a Card), even if the space is not connected to the Friendly Area.
Shields change ownership like Utilities.
Shields in empty spaces allow the space to be counted as part of the owning faction’s Friendly Area, but they do not render the space hostile to other factions.