WASHINGTON, Aug. 4 -- U.S. pilots who fired at a Croatian Serb missile site were acting in self-defense as a radar device locked onto their planes while they were flying over the embattled area at the request of U.N. military commanders, a NATO spokesman said. The NATO warplanes fired AGM-88 High-Speed Anti-Radiation Missiles, or HARM, at the site near Knin, the stronghold of the Serb rebels. NATO spokesman Jim Mitchell in Aviano, Italy, said the pilots were acting in self-defense and fired after their planes were illuminated by a radar from Serb surface-to-air missile system. Under present rules of engagement, NATO warplanes can fire without permission from the United Nations if they see a perceived threat. No immediate damage assessment was available after the 7 p.m. incident. Mitchell said U.S. Navy planes were patrolling the area after U.N. military commanders requested a NATO air presence. The request was made after Croatian government forces, overran U.N. posts, killing a peacekeeper and wounding two others. The Croatian troops had launched a major offensive in an apparent bid to retake the Krajina area, which the Serbs seized in 1991, when Croatia broke away from Yugoslavia. NATO officials said no missiles were launched from the Serb site, which they believe to be a Russian-built SA-6 anti-aircraft missile system. The U.S. planes returned safely to the aircraft carrier USS Theodore Roosevelt stationed in the Adriatic Sea, off the coast of Croatia. The pilots were flying EA-6B Prowlers -- electronic warfare aircraft that provide an umbrella of protection over strike aircraft and ships by jamming enemy radar, electronic data links and communications.
Their primary mission is to support airstrikes and ground troops by degrading enemy radar. The HARM missiles they fired are air-to-surface tactical weapons designed to seek out and destroy enemy radar-equipped defense systems such as the Russian-built SA-6, which is the predominant anti-aircraft system used by Bosnian and Croatian Serbs in the former Yugoslavia. The missile homes in on enemy radar emissions to locate its target. It was used extensively by the United States during the Gulf War in 1991.