Electronic Support Measures (ESM) a type of electronic warfare used to support allied units. It is featured in Ace Combat 6: Fires of Liberation and Ace Combat Infinity. In Ace Combat 6: Fires of Liberation, ESM is provided by allied units such as radar vehicles, radar facilities, AWACS, and some naval ships. When player or other friendly aircraft enter the effective range of friendly ESM, which is marked by a pulsating blue circle on the radar, their missiles' homing capabilities and rate of fire will increase. The effectiveness is indicated by the ESM level at the bottom right corner of the HUD.