This report describes virtual reality technology, which uses three-dimensional user-generated content, and its use by the U.S. military and intelligence community for training and other purposes. Both the military and private sector use this new technology, but terrorist groups may also be using it to train more realistically for future attacks, while still avoiding detection on the Internet. The issues for Congress to consider may include the cost-benefit implications of this technology, whether sufficient resources are available for the communications infrastructure needed to support expanded use of virtual reality technology, and whether there might be national security considerations if the United States falls behind other nations in developing or adopting this new technology. This report will be updated as events warrant.