This article examines the impact of a natural disaster on the political dynamics of an ethno-nationalist conflict. The humanitarian space generated by the 2004 tsunami could have revived the peace process between the Sri Lankan state and the Liberation Tigers of Tamil Eelam (LTTE), as evidenced by the joint mechanism that was formed for rehabilitation and reconstruction. However, the impact of the tsunami carried a potential for both peacebuilding and escalation of the conflict. The growing securitization of South Asia, led by the United States, upheld a militaristic approach and strengthened the Sri Lankan state against the LTTE. The militaristic approach to the decades-long conflict was advanced and eventually resulted in a massive war which claimed thousands of lives. The tsunami was a missed political opportunity.