I never knew the word was connected with the Spartans. Awesome:
“concise, abrupt,” 1580s, probably via L. Laconicus, from Gk. Lakonikos, from Lakon “person from Lakonia,” the district around Sparta in southern Greece in ancient times, whose inhabitants were famously proud of their brevity of speech. When Philip of Macedon threatened them with, “If I enter Laconia, I will raze Sparta to the ground,” the Spartans’ reply was, “If.”
One source of this story is Plutarch’s On Talkativeness.