This paper explores the impact of the 1991 Mt Pinatubo eruption on the US-Republic of the Philippines military relations through the lens of disaster diplomacy. Disaster diplomacy focuses on how and why disaster-related activities (e.g. mitigation, prevention and response) do and do not yield diplomatic gains, looking mainly at disaster-related activities affecting diplomacy rather than the reverse. Disaster diplomacy 'pathways', identified in previous studies, help to explain how the Filipino and US governments approached the negotiations for renewing the lease of the US military facilities in the Philippines in the context of two bases being damaged by a volcanic eruption. The paper further addresses six underpinning questions of disaster diplomacy for this case study. These questions assist in answering this paper's central research question: how much did the 1991 eruption of Mt Pinatubo influence US-Philippines military cooperation due to the concurrent diplomatic talks between the two governments regarding the lease renewal for the US bases in the Philippines? The answer is that disaster-related activities due to the Mt Pinatubo eruption had a short-term impact on US-Philippines diplomacy. This impact was seen in the context of significant connections already existing, through the long-standing US-Philippines military links. Over the long-term, non-disaster factors had a more significant impact on US-Philippines military diplomacy than Mt Pinatubo, adding to the list of case studies for which disaster diplomacy's impact was limited.