This Note is divided into five parts. Part I explores the history of psychological operations broadly, examining how information has been used to manipulate adversaries and foreign populations. Part II examines the development of technology and how social media has changed the way psychological operations are employed during peacetime to shape attitudes and intervene in sovereign affairs. Part III examines the current legal framework surrounding psychological operations and demonstrates how the gaps in that framework create legal grey zones for states to exploit through the use of disinformation on social media. Part IV discusses the role of international agreements in qualifying state use of “weaponized social media” as a prohibited intervention. It then considers the design of a multilateral treaty that addresses the limits of acceptable deliberate state behavior on social media when the use is intended to manipulate foreign populations during peacetime. This Note concludes by addressing the threat of emerging technologies and the need to reach an international consensus regarding permissible online behavior.