It is allowed for every Muslim to serve his country in any field which does not do injustice on others. Your country's interest should be in the interest of people and should not support the aggressors who might be friendly with some of your political leaders. You as a Muslim are obliged to serve peaceful people in your country and every where, and never support injustice. Our case as Muslims is the justice for all human beings and even for everything. Justice for people of Palestine for example, might not be an aim for many western politicians, but we must do everything possible in peaceful and legal way to support justice. Muslim officer must be an ethical officer and not just a blind officer.