put up a front(to take on a false or deceptive appearance (Merriam-Webster): He wouldn't hurt a fly, but he has to put up a front because his name's Poppet. One can readily appreciate that when a dog hears himself addressed day in and day out as Poppet, he feels he must throw his weight about. His self-respect demands it. (P.G. Wodehouse)ART Vancouver)
sow confusion("[The fire alarm] had been activated shortly before the shots began, perhaps an effort by the gunman to sow confusion." (NYT)Yuri Ginsburg)