To unlock different endings, complete the required task during the final mission before the bomb is disarmed.

Code - Effect

Ending A (Good Ending) - Have NSA trust above 33% and save at least two of the three targets
Ending B (Normal Ending) - Have NSA trust below 33% and save all three of the targets OR save only one target and have NSA trust above 33%
Ending C (Bad Ending) - Destroy all three targets OR destroy two targets and have NSA trust below 33%