As ISTflyer says, w/o checked baggage it should be no problem if your inbound flight is not delayed.

But with checked bags 2 hours may be cutting it close. 8-9am is not really Int'l rush hour at IAD - even with the a380 arriving at that time. However, you will need to get on the mobile lounge and go to Int'l Arrivals Building at the main terminal for passport and customs. W/o checked baggage, and assuming you will have mobile boarding pass, you can access the TSA checkpoint directly from Int'l Arrivals/baggage claim level (either by doors near carousel 13 or carousel 7 - do not have to go upstairs). But if you have checked bags, or need to checkin or get boarding passes, you will need to go upstairs to drop bags or check-in (I know there are some checkin kiosks tucked away on the lower levels but I don't recall exactly where they are or if they are AA). After dropping bags you will then go through TSA security and back out to the gates.

So, if getting to your next destination is not time critical and you have options if you miss the outbound flight, then I would be comfortable doing it. But if you absolutely, positively must be there by a certain time, I would build more time to make the connection.