Since April 2016, Mr. Tilden has served as the Associate Administrator for Counterterrorism and Counterproliferation with responsibility in preparing for, responding to, and successfully resolving nuclear and radiological accidents and incidents worldwide. The mission scope includes providing expertise, technically informed policy recommendations required to advance U.S. nuclear counterterrorism and counterproliferation objectives, understanding nuclear threat devices (i.e., improvised nuclear devices, proliferant devices, and lost or stolen nuclear devices outside of state control), leveraging the Department’s and NNSA’s existing nuclear expertise and science technology and engineering (ST&E) capabilities to support relevant whole-of-government activities and deployable assets for both nuclear incident response and nuclear forensics activities. Prior to this, from July 2012, Mr. Tilden served as the Deputy Associate Administrator for the same office. From December 2008 to July 2012, Mr. Tilden served as the director, Office of Nuclear Threat Science (formerly the Office of Nuclear Counterterrorism), leading an integrated technical staff of federal, contractor, and national laboratory personnel that executed the multi-laboratory Nuclear Counterterrorism Program, charged with the evaluation of a wide range of nuclear threat devices, including Improvised Nuclear Device concepts and designs.

From June 2008 to December 2009, Mr. Tilden was the Intelligence and Security Advisor to the Deputy Under Secretary for Counterterrorism and the National Nuclear Security Administration’s Office of Nuclear Counterterrorism. From 2004 to 2008, Mr. Tilden was the director of the Counterterrorism Division (CTD), within the Energy Department’s Office of Intelligence and Counterintelligence, which was responsible for providing technical intelligence analysis on; terrorist radiological and nuclear capabilities; potential terrorist threats to nuclear facilities, materials, and activities; and worldwide nuclear materials holdings and their security (Nuclear Materials Information Program – NMIP). From 2003 to 2004, Mr, Tilden was an intelligence and program analyst for the Office of Security Policy advising on Design Basis Threat policies for the department. Mr. Tilden is a retired Chief Warrant Officer (Counterintelligence and All-Source Intelligence) and served in both active and reserve capacities including Desert Shield/Desert Storm and Enduring Freedom/Noble Eagle. Mr. Tilden graduated from the University of Maryland in 1990 and completed post-graduate studies in strategic intelligence from DIA’s Joint Military Intelligence College in 1999. He is the proud father of Addison, a recent graduate of Salisbury University.