The Assistant to the Secretary of Defense for Public Affairs, or ATSD (PA), is the principal staff advisor and assistant to the Secretary of Defense and Deputy Secretary of Defense for public information, internal information, community relations, information training, and audiovisual matters in support of Department of Defense activities, leading a worldwide public affairs community of some 3,800 military and civilian personnel. The Assistant to the Secretary follows the Secretary's Principles of Information in providing Defense Department information to the public, the United States Congress and the media.

John F. Kirby is a retired United States Navy rear admiral serving as White House National Security Communications Advisor since 2024. He previously served in the Biden administration as Pentagon Press Secretary and Assistant to the Secretary of Defense for Public Affairs from 2021 to 2022 and as Coordinator for Strategic Communications at the National Security Council in the White House from 2022 to 2024. He worked as a military and diplomatic analyst for CNN from 2017 to 2021. He served in the Obama administration as Pentagon Press Secretary from 2013 to 2015 and as the spokesperson for the United States Department of State and Assistant Secretary of State for Public Affairs from 2015 to 2017.