His research interests have also included open-source intelligence, using and promoting the use of analysis of satellite images, photography, and other information sources to understand events and issues in proliferation and related topics.
[7] 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).
On April 27, 2017, Lewis dismissed the notion, promoted by Peter Vincent Pry[19] and others, that North Korea could seriously harm the United States with an EMP weapon.
[25] 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.
He additionally contributes to Foreign Policy – ForeignPolicy.com columnist since 2013.,[28] and to 38 North, an online journal on published by the US-Korea Institute at the Paul H. Nitze School of Advanced International Studies at Johns Hopkins University.