GPS Signals Jammed During Tank Trials

Lieutenant Colonel Lester W. Grau, US Army, Retired

Based on 6 August 2000 reports in The Sunday Times of London, Agence France-Presse and the 25 September 2000 Elevtheros Tipos, Athens

The highly accurate Global Positioning System (GPS) supports modern ground forces as they move and shoot. Maps and compasses stay in cases as digitized forces quickly use GPS to determine their location and the enemy’s. Although map-reading skills atrophy, few worry that GPS may suddenly provide erroneous information or cease working. Still, US Army equipment has already faced attacks on GPS functions—by allies.

In August 2000 the Greek government sponsored a tank competition at Litokhoro to determine the Greek army’s next tank—a deal worth $1.4 billion for 250 tanks. Competitors included the British Challenger 2E, the US M1A1 Abrams, the German Leopard 2A5 and the French Leclerc. During the trials, the British and US tanks had navigation problems despite using multiple GPS satellites to determine their positions precisely. After the embarrassing performance, officials discovered that the GPS satellites were being jammed—by a French security agency. Less than a foot high, the jammers transmitted stronger signals than satellites on the same frequency. The jammers were reportedly hidden on the firing range and remotely activated as US and British tanks were tested.

Greek defense officials found the jamming episode rather amusing and discounted the associated technical problems. The threat remains: if an ally can create such havoc during a test, what effect could hostile GPS jamming have during combat?