Its called Patriotism Arayser. This shit doesn't happen in America every day, or every other day, or every week. Its not supposed to happen here, period. Who gives a fuck about Iraq? Every day those assholes are killing themselves, suicide bombing churches and coffee shops, and raping people in mass groups. There is a huge difference between that country, and ours. We care, because if it can happen there, it can happen anywhere. That means we have the potential to be the next victim. Will it happen anytime soon? Probably not, but you can't be sure.
So, thats why we care. It direct relates to us, and we see American's, including children, being injured in this attack, and it strikes a nerve. When it happens in Iraq, we expect it. Its not expected here. We assume it was an attack on our nation, one that we've been raised from Day 1 to love and defend. That is why it is different when shit happens here, instead of Iraq. This was a national tragedy, which we still have no idea for whom is responsible.