 Raytheon Missile Systems developed Vigilant Eagle under a U.S. Defense Department contract and has discussed with the Department of Homeland Security, the potential of using it at U.S. airports.In 2006, a $4.1 million contract with the Department of Homeland Security was issued to assess the anti-missile system.Within the last three years, the company's researchers have shot down multiple types of shoulder-fired antiaircraft missiles at a distance of several miles with pulses of microwave energy.