He is Professor of Public International Law at the University of Reading, the G. Norman Lieber Distinguished Scholar at the Lieber Institute of the United States Military Academy at West Point, and the Charles H. Stockton Distinguished Scholar in Residence at the US Naval War College.

In 1999, he was appointed Professor of International Law at the George C. Marshall European Center for Security Studies in Garmisch, Germany, eventually becoming Dean.

In addition to his position at the University of Reading, he is G. Norman Lieberman Distinguished Scholar at West Point, Strauss Center Distinguished Scholar and Visiting Professor of Law at the University of Texas, Charles H. Stockton Distinguished Scholar in Residence at the United States Naval War College's Stockton Center for International Law, and Senior Fellow at the NATO Cooperative Cyber Defence Centre of Excellence.

Its programs are sponsored by numerous nations and international organizations and certified as Executive Education by the University of Reading.

In 2017 he was awarded the Order of the Cross of Terra Mariana by the President of Estonia for his contributions to cyber security.