Though it is unclear how much Smith knew of the Danites' activities, he clearly approved of those of which he did know. After Rigdon delivered a sermon that implied dissenters had no place in the Latter Day Saint community, the Danites forcibly expelled them from the county.
Smith seemed to be knowledgeable about the Danites' activities, even if the extent of his knowledge was unclear. He clearly supported those actions he was familiar with. Following Rigdon's sermon that implied dissenters were unwelcome in the Latter Day Saint community, the Danites forcibly removed them from the county.