Robert Smolen, a former Air Force officer and top arms control official at the White House National Security Council, Wednesday was sworn in as deputy administrator for defense programs at the National Nuclear Security Administration, the semi-autonomous weapons agency in the Energy Department.

Smolen steps into the key position as the agency, known as NNSA, faces major questions on Capitol Hill about its plan to consolidate DOE’s nuclear weapons complex and build its proposed Reliable Replacement Warhead. Congressional Democrats, in particular, have suggested the consolidation plan does not go far enough and the replacement warhead is not needed.

Smolen also faces safety and security issues in the complex that threaten NNSA efforts to stay on track in maintaining aging warheads without underground testing, and ramping up production of new plutonium pits at Los Alamos National Laboratory, N.M.

Smolen, whose nomination was confirmed by the Senate Nov. 16, retired from the Air Force in August after serving as commander for the Air Force District of Washington. Prior to that, Smolen was director for strategic policy and arms control at the National Security Council.

From 1998-2004, Smolen held various positions at the Pentagon, including director of nuclear and counterproliferation for the Air Force headquarters and director for manpower and personnel for the Joint Chiefs of Staff.