Beginning in 2016, the Japanese Ministry of Health, Labour and Welfare (MHLW) began stationing liaisons within the US Department of Health and Human Services (HHS) Administration for Strategic Preparedness and Response to strengthen cooperation on bilateral health security engagement and collaboration. Notable accomplishments include the establishment of the US-Japan Health Security Committee and collaborations between the US-Japan Disaster Medical Assistance Team on mass event responses, such as the repatriation of American citizens from the Diamond Princess in February 2020 and the COVID-19 response. Japan has also embedded liaisons at the US Centers for Disease Control and Prevention to advance collaboration on public health. In 2021, with COVID-19 highlighting the importance of collaboration on pandemic preparedness, MHLW established a liaison program with the US National Institute of Allergy and Infectious Diseases. These liaisons with HHS agencies have paid dividends to health security collaboration, particularly by enabling greater connections between technical experts in MHLW and HHS.