From 2007 to 2010, Lewis directed the Nuclear Strategy and Nonproliferation Initiative at the
New America Foundation. From 2006 to 2007, he was Executive Director of the Managing the Atom Project at the
Belfer Center for Science and International Affairs at
Harvard University. Since 2010, Lewis has been the Director of the East Asia Nonproliferation Program at the James Martin Center for Nonproliferation Studies at MIIS in Monterey, California, and an adjunct professor at MIIS. Research topics have included nuclear proliferation and weapons programs of China, North Korea, Iran, and other states, and open-source intelligence performed by the policy community itself (see for example
Eliot Higgins). He has worked with graduate students and MIIS and other researchers to develop tools and provide training on tools and technology for open source intelligence. He is also an affiliate with the
Stanford University Center for International Security and Cooperation.
North Korea Lewis has extensively written and spoken, including for media reports, on the weapons tests, development program, and missile programs of North Korea, a country covered by the East Asia Nonproliferation Program. Lewis has written specifically about North Korea's nuclear materials production; weapons design choices (including nuclear weapon size/
miniaturization and use of fissile uranium or plutonium in warheads); missiles and the North Korean space program; North Korea's missile press coverage, propaganda, and misinformation. He makes frequent use of open source intelligence from satellite and press/propaganda images and stories. On April 27, 2017, Lewis dismissed the notion, promoted by Peter Vincent Pry and others, that North Korea could seriously harm the United States with an
EMP weapon.
China One of the countries covered by the East Asia Nonproliferation Program, China has been a focus for Lewis, including his two books and monograph. His books ''Paper Tigers: China's Nuclear Posture
(2014) and The Minimum Means of Reprisal: China's Search for Security in the Nuclear Age'' (2007) examine China's nuclear weapons and missiles policies. He wrote, podcasted, and was cited in mainstream press coverage in 2015 rebutting claims that China's adding
MIRVs to its larger missiles was a dangerous escalation, arguing instead that it was a natural evolution for the Chinese older, larger missile force. He has also studied and written about China's nuclear program as it relates to other powers such as India. Lewis has also written on China's conventional weapons program, including antiship and conventional ballistic missile programs and their testing of a
hypervelocity weapon system. In November 2024, Lewis was part of a team of open source researchers at the
Middlebury Institute of International Studies at Monterey that identified the location of China's land-based prototype nuclear reactor for a large surface warship near
Leshan, Sichuan province, concluding that it was for a
nuclear-powered aircraft carrier. == Publications ==