This mission gives you two days and twenty-one hours to eliminate the last base, so work quickly. Move your units east and set up a base.
Defenses are unnecessary.
Build a Missile Control Center with four missile silos and wait until you have enough credits to load each. After you're fully armed at the missile base, take a lone helicopter and scout out your objective. The silo base lies in the map's southwest corner. When you have your targets, place the crosshairs on the enemy buildings and launch four ballistic missiles into the base. If they're nuclear-tipped, you'll level it.