John Charles Rood (born 1968) is an American national security adviser and former government official who served as the Under Secretary of Defense for Policy from January 2018 to February 2020.

[2] Rood also served as Acting Under Secretary of State for Arms Control and International Security from September 2007 to January 2009, and as Assistant Secretary of State for International Security and Nonproliferation from October 2006 to September 2007.

[3][4][5] On October 16, 2017, Rood was nominated by President Donald Trump to become the Under Secretary of Defense for Policy.

In January 2018, Secretary James N. Mattis released the National Defense Strategy (NDS) which placed the order of priorities for the Department of Defense as China, Russia, North Korea, Iran and then Countering Terrorism.

As the Under Secretary of Defense for Policy, Rood was responsible for the implementation of the NDS worldwide.