This thesis seeks to examine and analyze the manifestations of the ontological security and self-identity anxiety of the Thai states through its rhetoric in relation to Thai and Malayu Muslims. The main question being posed in this thesis is how the Thai state justified the use of force during the Tak Bai Incident in 2004 and the Ratchaprasong bombing in 2015. This thesis examines the rhetoric of the Thai state through speeches and media before, during, and after in the selected cases. Such rhetoric involves the framing and constructions of "Thainess" or Thai identity in relation to the "other" or Thai and Malayu Muslims during the events. This framing is related to ethno, religious, and cultural nationalism and draws on those narratives. The theory that this research draws from is the Ontological Security theory by Jennifer Mitzen and Brent Steele which allows us to analyze the Thai state's actions and identity construction during the events. Ontological security is the security of the self, which all states strive for since it is linked to self-identity constructions. States will take actions that are at times detrimental to the physical self in order to protect ontological security because it is crucial to its survival. The methodological approach draws from Roxanne Lynn Doty's Discursive Practices Approach which allows us to examine how power and roles are constructed from rhetoric. The key results show that both the Tak Bai Incident and Ratchaprasong bombing disrupted the Thai state's ontological security and self-identity construction. In response, the Thai state engages in security-seeking behavior by reconstructing its self-identity in relation to the Thai and Malayu Muslims in order to regain its sense of ontological security. In doing so, the Thai state and media use rhetoric such as "Farang" and "Khaek" to define the Thai and Malayu Muslims as different and inferior subjects to the Buddhist majority. This enables the Thai state to justify its use of force in order to regain control over its compromised ontological security by way of military actions and violence. We see that the Thai state's perception of ontological security derived from its attachment to routines which had now been associated with the attachment to the conflict. This attachment had allowed the Thai state a sense of certainty since it knew how to act in the face of challenges. Attachment to routines thus allows the Thai state to dispel uncertainty which causes disruptions to its self-identity by creating anxiety. In analyzing the Thai state's rhetoric during these events, various identities of who is and is not Thai can be noted. These are then used to justify and legitimate the use of force by the Thai state as it seeks to protect and safeguard its ontological security. / Master of Arts / This thesis aims to understand how the construction of self-identity of the Thai state manifested in rhetoric. In particular, the Thai state's relationship towards the "other" or in this case the Thai and Muslim Malayu population in the three southern provinces of Thailand. This research attempts to understand how the rhetorics involving "Thainess," "Farang," and "Khaek" play a role in the conception of Thai identity. In particular, the way these rhetoric manifest themselves in both the media and the official channels. This research utilizes the Ontological Security Theory and the Discursive Practices Approach to analyze the rhetoric found in the two cases of the Tak Bai incident in 2004 and the Ratchaprasong bombing in 2015. This analyzed rhetoric allows us to understand the way ontological security manifests itself in the Thai state when its self-identity is challenged by the "other." The research results show that both cases present a challenge to the Thai state's self-identity construction and ontological security routines. Once disrupted the Thai state uses force to subdue the source of the challenge, which was the presence of the Thai and Malayu Muslims. We see that this examined rhetoric by the Thai state created an environment and conditions, which enables the justification of force to protect its sense of self-identity and ontological security. Lastly, this research is important since it allows us to understand how states, such as the Thai state, behave and justify force against minority groups. It further enables us to see a state's behavior from a physical security standpoint and an ontological security one. It shows that language can be the window to the behavior of a state and regime that feels insecure by its encounter with the "other."