The Boeing system has been built and tested near Sasabe, which is southwest of Tucson, Arizona. The area is a frequently used site of illegal immigrants and drug smugglers.

The high-tech system uses infrared cameras, ground radar, and sound sensors, including motion sensing devices. The system also uses nine 100-foot (30-eter) tall unmanned surveillance towers, which hold the sensing devices and cameras. 

The cameras and sensors (including motion detection sensors) are able to identify people from about ten miles (16 kilometers) away. It can also identify what these people are carrying, possibly showing if illegal drugs are being carried across the border.

The Sasabe test site is a 28-mile (48-kilometer) distance between Arizona and Mexico. The test system cost $20 million to design and build.

Homeland Security secretary Michael Chartoff says the virtual fence has already proven itself beneficial in catching illegal immigrants and drug smugglers.

A representative of The Boeing Company stated on February 22, 2008, "2000 illegal immigrants were apprehended in five months." [New Scientist magazine, March 1-7, 2008]

Future plans are to extend the virtual fence to other border areas in Arizona and Texas. A total of 770 miles (1,130 kilometers) of virtual fence, including 1,800 unmanned surveillance towers, are planned and have been approved by the U.S. government.

The series of towers will provide U.S. border patrols with a way to recognize locations where people are crossing the border and help in their ability to intercept the intruders.

The virtual fence has its critics. Many critics state that the technology will not be effective at catching illegal immigrants and drug smugglers crossing borders between the United States and Canada and Mexico.

Critics also point out past government failures in management and politics at securing the U.S. borders.

The cost of the total project, what is called the Secure Border Initiative, has been estimated at $2 to $2.5 billion.

What does the Homeland Security Department say about its Secure Border Initiative? Please read on.