From 6 to 10 June 2011, NATO and Russian fighter aircraft will take part in counterterrorism exercise “Vigilant Skies 2011” - a joint demonstration of the NATO-Russia Council Cooperative Airspace Initiative (NRC CAI). This initiative is designed to prevent terrorist attacks which use civilian aircraft, such as the attacks on the World Trade Center on September 11, 2001, by sharing information on movements in NATO airspace and Russian airspace, and by coordinating interceptions of renegade aircraft.