As a Soldier, what are the obligations to report a sexual harassment if I am aware (not a witness) of it as a third party?

Generally speaking, if you are aware of something occurring within your ranks that goes against the Army values, then it is your obligation to speak up and report it to higher. Or, at the very least, speak to the person about it to eliminate the problem at the lowest level.

Your obligations is to SAY SOMETHING

Talk to the EO rep. An investigation can be done internally or officially with the Division. Laws, rule, and regulations exist to help you decide on the correct course of action. We need to do our utmost to protect women from sexual harassment, especially since it is going up.