No need for war. Eff 'em and let them go, then close their northern border, shut down all federal facilities, services, funding, infrastructure (i.e. no connection to the national grid, for example), etc.
BTW, over on cielito azul, Chuck Tingle is also promoting his new book, Bury Your Gays, which you can preorder. He states it is "the queer horror novel that is so gay it gets you kicked out of texas. "
Just for that I think I need to add it to my #TBR to read.