Defence agency doesn`t give bonuses. Or i don`t understand how it works. When i as american try launch air, artillery or missle bonus from agencies not added

Unfortunately, the bonus strength from the defense agency is not reflected on the UI as it does not affect the combat strength of the units, only of the bombard action. This unfortunately means that when targeting large armies, the impact can be difficult to notice until you have several Defense Agencies, but the damage you deal should be increasing slightly for each.