Insurgents surging in from inside and outside

It seems that the military is pretty unclear on what an "insurgent" is, as well. As reported in the VOA News (that’s Voice of America) on Dec. 16, the top U.S. military commander in Iraq, General George Casey expressed " concern that insurgents are still infiltrating into Iraq from across its border with Syria. General Casey charged that former members of Saddam
Hussein’s regime are living in Syria and providing assistance to those
fighting the U.S.-led coalition. ‘We see a facilitation mode through
Syria for foreign fighters coming into Iraq.’"

Now which is it? Are the native Iraquis insurgents, or are foreign fighters (from, for instance, Saudi Arabia) actually the insurgents?

This may seem picayune, but it does seem important to know who we’re fighting.