evolving. what is a.m. goi what s going on with the shutdown which is imminent? what s happening with the defense secretary resigning in protest, giving the stated reasons for his resignation, given what appears to be the immediate precipitating event here, which appears to have been president trump s unilateral twitter announcement that all u.s. troops will immediately leave syria? one of the things we re going to need expert help on tonight with regard to that story is whether secretary mattis resignsing and resigning in this way, might be expected to cause a greater standoff of some kind between the president and the u.s. military. so we re going to get help on that tonight from an excellent pentagon based reporter, we ll be speaking with her in a moment. also we ll be talking with a presidential historian who is looking at what ace precedent there is in our history for this kind of thing, and what that might tell us about the prospects for some sort of more dramatic split between