Arming the Quad examines United States Security Cooperation via Foreign Military Sales (FMS) to the Quadrilateral Security Dialogue (Quad) partners – Australia, Japan, and India – amidst the U.S.-China strategic competition. In addition to the U.S., the Quad represents two long-standing U.S. allies (Australia and Japan) and a declared Major Defense Partner (India). Through a historical study, this research begins at the Quad’s founding (December 2004), continuing to the establishment of the trilateral security partnership between Australia, the United Kingdom, and the U.S., known as AUKUS – a significant milestone for U.S. arms sales in the Indo-Pacific (September 2021). This research finds that, in response to China’s expanded influence and rapid militarization, the U.S. adopted an Indo-Pacific strategy that increased interoperability via Security Cooperation with allies and partners, namely the Quad.