Gray Zone Defense Assessment Act This bill requires the President, the Department of State, and the Office of the Director of National Intelligence (ODNI) to each provide reports to Congress related to gray zone campaigns or assets. (Gray zone campaigns involve advancing a nation's interests through activities that fall between ordinary statecraft and open warfare without provoking a kinetic military conflict. Gray zone assets are entities or proxies used in gray zone activities.) Specifically, the bill requires the President to submit a report to Congress on the processes and capabilities by which the United States responds to gray zone campaigns and recommendations to enhance such processes and capabilities; requires the State Department to submit a report to Congress on the department's understanding of the gray zone threat environment and capacity to contribute to coordinated U.S. responses to adversary gray zone campaigns; and expands a required Intelligence Community Assessment regarding Russian gray zone assets to include the gray zone assets of China, Iran, North Korea, Cuba and Syria. (ODNI must submit this expanded assessment to Congress annually.)