They are simply the surface, visible, public and open wing of Al Queda - like the fiction that there is some division between the IRA political wing and IRA terrorists.
Follow the lives and educations of the founders of this Islamic political organization, together with the Islamic philosophers who taughgt them and you'll find the same people and Islamic religious sources that started bin Laden on his way.
There is not one bit of difference between this group and active Islamic terrorists, other than the difference in the roles they play in the same, universal, coordinated onslaught against the "west".
Yes, low key and LEGAL, even in the US.