We suspect quite a lot. And some of them have been in here for a long time.
The ongoing, fanatical Muslim Iranian régime, is principal source of Shi'ite related terrorism in the world, dating back to 1979.
If Tehran's tyrants could be overthrown, broadbased terrorism in Iraq would be reduced, terror groups such as Hizballah, Islamic Jihad & Hamas would lose arms shipments, coupled with jihadic training, not to mention removing the current Iranian nuclear arms threat.
Short timer -- Thanks for your service!