Walk straight ahead and use the elevator (#11). Move forward and eliminate every opponent in your range. After finding yourself on the surface, turn right and climb down on pipes. There are some armors (#12) waiting for you. Again, move straight ahead. After short walk, you'll get to the trenches. Kill all enemies and approach the soldiers from your team (#13).
Destroy Strogg Aircraft Hangars
Your team's task is to destroy big cannon that you can 'admire' from the trenches. To do that, first eliminate opponent's fighters (they are systematically sent from nearby hangars). Move with sergeant Morris and break through trenches, of course killing opponents on the way. The road ends after walking inside the complex (#14).