Back at the end of the 20^th century, Presidential Executive Order 13112 directed that all agencies monitor and minimize movement of non-indigenous invasive species. That was a tall order. The challenge has been interpreted with differing focus by different agencies. Those with activities taking place solely within the U.S. assumed that it applied to those activities. The U.S. Forest Service, for example, some time ago implemented the requirement to wash responding vehicles entering and leaving forest fire management areas. They also developed a prototype portable vehicle washing system to perform these tasks. The Department of Defense, probably sensitized by the issues relating to the return of equipment used in Operation Desert Storm in 1991, has largely focused on the need to clean vehicles being retrograded from overseas.  These concerns are clearly the more obvious ones, but this has left DoD and the Army without clear policy or guidance as it relates to measures appropriate for preventing the spread of invasive species from place to place within the continental United States. Both reserve components and regular Army units regularly travel from place to place for training. Construction and timber harvesting equipment are moved from one project to another every day. It is clear that many elements of risk are present when military vehicles, containers, and especially construction equipment are moved within the country, as well as internationally. What do we know about how severe this risk may be? And whether or not cleaning the equipment using available systems will help significantly? Our studies show that the risk may be reduced significantly, but present systems are not capable of eliminating it.