Last year, for example, a U.S. Air Force B-2 stealth bomber flying in to the Farnborough Air Show near London reportedly was detected by the IR glow of its aerodynamic heating. It is not hard to imagine using an IR sensor to trigger the launch of a command-guided missile, which might be coached toward the target. The F-117A is not particularly maneuverable, and probably lacks any sort of missile launch warner (other than a radar-warning device). The radio link used by a command-guided system could be jammed by an appropriate device (generally on board an EA-6B Prowler), but the F-117 presumably operated alone, on the theory that it was safe from such attack.
Several fighters, including the Russian-built MiG-29, have integrated IR search-track devices, which are sometimes likened to electro-optical radars that range on their targets using lasers. It seems reasonable to imagine that F-117s and other stealthy aircraft are vulnerable to IR detection, hence to attack by such fighters, which fire long-range missiles with IR seekers (mid-course guidance is command/inertial). It is possible that the F-117 loss indicates that stealth, at least as currently conceived, has serious limitations and that it may not be wise to depend on it in the design of such aircraft as the Joint Strike Fighter, whose designs presumably entail considerable sacrifices in performance in the name of limiting radar cross-section.
The Serbs reportedly benefited from the Iraqis, who have confronted F-117s and other U.S. aircraft in battle. During Operation Desert Storm, the Iraqis claimed that they had tracked F-117s over Baghdad but their statements were dismissed at the time because no F-117s were lost. Of course, this may have been caused by inefficiencies in an Iraqi air defense system unable to capitalize on the detection The only corroboration from the U.S. side was that F-117 pilots saw Iraqi Mirages equipped with searchlights. The obvious inference was that it took some sort of tracking and combat air direction to get the Mirages close enough to be seen by the F-117 pilots.
The loss of the F-117 over Serbia may mean that the Iraqi claims were not altogether specious, and that in fact stealth has been less successful than advertised. Perhaps it is time to re-evaluate stealth in aircraft design.