Why We Say Shalom Aleichem at Kiddush Levanah
A teaching ofRav Nosson Tzvi Finkelהרב נתן צבי בן משה פינקל
During Kiddush Levanah we first say that fear and dread should fall upon them. Those words could shape our souls toward rejecting others and seeking revenge. So we immediately say Shalom Aleichem to fix love and brotherhood firmly in our hearts.
Source: V'Ohr HaMussar, p. 205