Being a muslim in a foreign country is an increasingly difficult and isolating experience.
42% of young Muslims in France believe suicide bombings are justified (35% overall).
http://www.pewresearch.org/files/old-assets/pdf/muslim-ameri...
What happened today was not "civil unrest".
That's all well and good to say when you know enlisting in the US military in conventional warfare against ISIS has a good chance of succeeding.
But what if the US was the small poor state and ISIS was the world's largest economy whose military targets were too well-defended to attack?
I'm sure you'd find lots of recruits in Texas for "guerilla special units behind enemy lines". Especially if cruise missiles and drone strikes were hitting US soil every other day.