His areas of expertise include WMD nonproliferation, export controls, and foreign policy. Prior to joining Stimson, he served as the Special Coordinator for U.N. Security Council resolution 1540 in the Office of Counterproliferation Initiatives at the U.S. State Department from 2012 through 2016. As such, he led U.S. government efforts to further implementation of the more than two hundred legally binding obligations and recommendations of the resolution, which aims to combat proliferation of WMD and their means of delivery, especially to non-state actors such as terrorists and criminal organizations. From 2005 to 2012, he worked as an Expert for the Committee established pursuant to U.N. Security Council resolution 1540 (2004), a subsidiary body of the U.N. Security Council, monitoring and facilitating implementation of the resolution in all U.N. Member States, along with building relationships with more than forty international organizations, coordinating assistance activities, and conducting outreach with industry and academia. Elected coordinator of the Experts from 2010-2012, his also led the work in several specialized areas including combating the financing of proliferation and export controls.