A native of Charleston, South Carolina, Yonnick Hammond brings two decades of frontline experience influencing outcomes at the highest levels of the federal government. At Cassidy & Associates, he draws on a sophisticated command of both the Legislative and Executive Branches to help clients secure tangible, measurable wins in an increasingly complex policy environment. With deep expertise in missile defense and nuclear shipbuilding, Hammond offers a rare insider’s perspective on some of the nation’s most consequential defense programs—insight shaped by years of service within Congress and the Department of War.

Prior to joining Cassidy’s National Security and Defense Practice as a Senior Vice President, Hammond served as Deputy Director of Congressional Affairs at the Missile Defense Agency. In this role, he was a principal advocate for major missile defense programs executed by both traditional prime contractors and emerging non-traditional defense firms. He led the Agency’s day-to-day engagement strategy on Capitol Hill, successfully navigating intense congressional scrutiny during a period marked by historic milestones in U.S. missile defense—including the largest recent operational employment of missile defenses against Houthi and Iranian threats and the implementation of President Trump’s Golden Dome Executive Order.

Hammond previously served as a congressional liaison at Naval Reactors, a joint Department of Energy and Department of the Navy command. There, he played a central role in securing critical appropriations and legislative authorities necessary to deliver nuclear reactors on schedule for the Navy’s submarine and aircraft carrier fleet—capabilities that underpin U.S. strategic deterrence and global power projection.

On Capitol Hill, Hammond is equally recognized for his leadership and commitment to mentorship. He takes particular pride in developing junior legislative staff who have gone on to hold senior positions throughout Congress. His own legislative background includes service as a Legislative Assistant to the Chairman of the House Republican Conference and as Legislative Director for a member of the House Armed Services Committee—experience that provides him with a durable, practical understanding of how Congress truly operates and how to achieve results when stakes are highest.