judging by the screenshot of a rookie, I assume he's after promotions
..
Apparently one single not terrain-damaging explosion at 1:18:30 in this video was enough to cause the loss of all three hangars: https://www.twitch.tv/videos/2179774439?t=01h18m24sAlternatively, coulda been me shooting off a Multi-Launcher (again, no visible terrain damage) at the Access Lift. Heh.
Yep, you gotta be careful in base defence missions.