Lee is a former Group Leader at MIT Lincoln Laboratory, where he established the Cyber System Assessments Group, which became a nationally recognized centre of excellence. He led the group in cyber range development, cyber test and evaluation, cyber red teaming, and cyber exploitation as well as the deployment of the LARIAT traffic generation tool. As Group Leader, Lee worked with DARPA, testing, and evaluating over 30 classified and unclassified programs. He also worked with the Air Force.

Lee led several national studies for the Department of Defense to identify and assess existing capabilities, develop an approach and roadmap for their consolidation and advancement and provide the roadmap for the future, which laid the foundation for the National Cyber Range Complex, the Persistent Cyber Training Environment, and other specialized testing and training facilities.

Since 2015, Lee has served as the Chief Technology Officer and Co-Founder at SimSpace. The SimSpace platform is being used as the solution for USCYBERCOM’s Persistent Cyber Training Environment and for other militaries around the world as well as many commercial customers.